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Document and Entity Information	9 Months Ended
Document and Entity Information	Jun. 30, 2020 shares
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	MESA
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	NV
Entity File Number	001-38626
Entity Tax Identification Number	85-0302351
Entity Address, Address Line One	410 North 44th Street
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Phoenix
Entity Address, Postal Zip Code	85008
City Area Code	602
Local Phone Number	685-4000
Entity Address, State or Province	AZ
Entity Registrant Name	MESA AIR GROUP, INC.
Entity Central Index Key	0000810332
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding	35,414,284

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Current assets:
Cash and cash equivalents	$ 64,934	$ 68,855
Restricted cash	3,444	3,646
Receivables, net	14,618	23,080
Expendable parts and supplies, net	22,418	21,337
Prepaid expenses and other current assets	7,143	40,923
Total current assets	112,557	157,841
Property and equipment, net	1,233,727	1,273,585
Intangibles, net	8,407	9,532
Lease and equipment deposits	2,121	2,167
Operating lease right-of-use assets	131,480
Other assets	7,021	8,792
Total assets	1,495,313	1,451,917
Current liabilities:
Current portion of long-term debt and financing leases	176,896	165,900
Current maturities of operating leases	43,219
Accounts payable	39,918	49,930
Accrued compensation	10,350	11,988
Other accrued expenses	37,663	28,888
Total current liabilities	308,046	256,706
Noncurrent liabilities:
Long-term debt and financing leases, excluding current portion	586,877	677,423
Noncurrent operating lease liabilities	71,068
Deferred credits	9,355	12,134
Deferred income taxes	61,203	55,303
Deferred revenue, net of current portion	12,240
Other noncurrent liabilities	1,030	24,483
Total noncurrent liabilities	741,773	769,343
Total liabilities	1,049,819	1,026,049
Commitments and contingencies (Note 15 and Note 16)
Stockholders' equity:
Preferred stock of no par value, 5,000,000 shares authorized; no shares issued and outstanding
Common stock of no par value and additional paid-in capital, 125,000,000 shares authorized; 35,414,284 (2020) and 31,413,287 (2019) shares issued and outstanding, 0 (2020) and 3,600,953 (2019) warrants issued and outstanding	241,782	238,504
Retained earnings	203,712	187,364
Total stockholders' equity	445,494	425,868
Total liabilities and stockholders' equity	$ 1,495,313	$ 1,451,917

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Sep. 30, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	35,414,284	31,413,287
Common stock, shares outstanding	35,414,284	31,413,287
Common stock, warrants issued	0	3,600,953
Common stock, warrants outstanding	0	3,600,953

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating revenues:
Total operating revenues	$ 73,099	$ 180,224	$ 437,030	$ 535,527
Operating expenses:
Flight operations	29,664	53,025	135,199	155,636
Fuel	146	211	504	433
Maintenance	22,591	54,322	145,021	139,504
Aircraft rent	15,582	12,875	39,196	41,104
Aircraft and traffic servicing	538	978	2,938	2,977
General and administrative	11,737	12,435	39,233	38,121
Depreciation and amortization	20,635	19,761	61,656	57,528
Lease termination		9,540		9,540
CARES Act grant recognition	(43,018)		(43,018)
Total operating expenses	57,875	163,147	380,729	444,843
Operating income	15,224	17,077	56,301	90,684
Other (expenses) income, net:
Interest expense	(10,368)	(13,496)	(34,668)	(42,110)
Interest income	1	733	95	1,188
Loss on extinguishment of debt				(3,616)
Other income (expense), net	79	(451)	720	82
Total other (expense), net	(10,288)	(13,214)	(33,853)	(44,456)
Income before taxes	4,936	3,863	22,448	46,228
Income tax expense	1,517	856	6,359	10,891
Net income	$ 3,419	$ 3,007	$ 16,089	$ 35,337
Net income per share attributable to common shareholders
Basic	$ 0.10	$ 0.09	$ 0.46	$ 1.02
Diluted	$ 0.10	$ 0.09	$ 0.46	$ 1.01
Weighted-average common shares outstanding
Basic	35,299	34,835	35,154	34,683
Diluted	35,299	35,112	35,248	35,051
Contract Revenue [Member]
Operating revenues:
Total operating revenues	$ 71,648	$ 170,366	$ 409,228	$ 510,586
Pass Through and Other [Member]
Operating revenues:
Total operating revenues	$ 1,451	$ 9,858	$ 27,802	$ 24,941

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Revision of Prior Period Accounting Standards Update Adjustment [Member]	Common Stock [Member]	Number of Warrants [Member]	Common Stock and Additional Paid-In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Revision of Prior Period Accounting Standards Update Adjustment [Member]
Beginning balance at Sep. 30, 2018	$ 374,467				$ 234,683	$ 139,784
Beginning balance, shares at Sep. 30, 2018			23,902,903	10,614,990
Stock compensation expense	1,454				1,454
Stock issuance costs	157				157
Net income	19,081					19,081
Ending balance at Dec. 31, 2018	395,159				236,294	158,865
Ending balance, shares at Dec. 31, 2018			23,902,903	10,614,990
Beginning balance at Sep. 30, 2018	374,467				234,683	139,784
Beginning balance, shares at Sep. 30, 2018			23,902,903	10,614,990
Net income	35,337
Ending balance at Jun. 30, 2019	412,734				237,613	175,121
Ending balance, shares at Jun. 30, 2019			30,361,168	4,603,333
Beginning balance at Dec. 31, 2018	395,159				236,294	158,865
Beginning balance, shares at Dec. 31, 2018			23,902,903	10,614,990
Stock compensation expense	1,298				1,298
Repurchased shares and warrants	(449)				(449)
Repurchased shares and warrants, shares			(52,967)
Stock issuance costs	28				28
Warrants converted to common stock			3,834,693	(3,834,693)
Restricted shares issued, shares			284,846
Net income	13,249					13,249
Ending balance at Mar. 31, 2019	409,285				237,171	172,114
Ending balance, shares at Mar. 31, 2019			27,969,475	6,780,297
Stock compensation expense	1,507				1,507
Repurchased shares and warrants	(1,065)				(1,065)
Repurchased shares and warrants, shares			(116,757)
Warrants converted to common stock			2,176,964	(2,176,964)
Restricted shares issued, shares			331,486
Net income	3,007					3,007
Ending balance at Jun. 30, 2019	412,734				237,613	175,121
Ending balance, shares at Jun. 30, 2019			30,361,168	4,603,333
Beginning balance at Sep. 30, 2019	425,868				238,504	187,364
Beginning balance, shares at Sep. 30, 2019			31,413,287	3,600,953
Stock compensation expense	1,320				1,320
Repurchased shares and warrants	(41)				(41)
Repurchased shares and warrants, shares			(5,558)
Warrants converted to common stock			1,612,481	(1,612,481)
Restricted shares issued, shares			18,916
Net income	10,785					10,785
Ending balance at Dec. 31, 2019	438,191				239,783	198,408
Ending balance (ASU 2018-09 [Member]) at Dec. 31, 2019		$ 259					$ 259
Ending balance, shares at Dec. 31, 2019			33,039,126	1,988,472
Beginning balance at Sep. 30, 2019	425,868				238,504	187,364
Beginning balance, shares at Sep. 30, 2019			31,413,287	3,600,953
Repurchased shares and warrants			$ (500)
Net income	16,089
Ending balance at Jun. 30, 2020	445,494				241,782	203,712
Ending balance, shares at Jun. 30, 2020			35,414,284
Beginning balance at Dec. 31, 2019	438,191				239,783	198,408
Beginning balance, shares at Dec. 31, 2019			33,039,126	1,988,472
Stock compensation expense	1,193				1,193
Repurchased shares and warrants	(160)				(160)
Repurchased shares and warrants, shares			(18,244)
Warrants converted to common stock			1,988,472	(1,988,472)
Restricted shares issued, shares			141,614
Employee share purchases	243				243
Employee share purchases, shares			43,934
Net income	1,885					1,885
Ending balance at Mar. 31, 2020	441,352				241,059	200,293
Ending balance, shares at Mar. 31, 2020			35,194,902
Stock compensation expense	1,020				1,020
Repurchased shares and warrants	(297)				(297)
Repurchased shares and warrants, shares			(88,785)
Restricted shares issued, shares			308,167
Net income	3,419					3,419
Ending balance at Jun. 30, 2020	$ 445,494				$ 241,782	$ 203,712
Ending balance, shares at Jun. 30, 2020			35,414,284

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 16,089	$ 35,337
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization	61,656	57,528
Stock compensation expense	3,533	4,259
Deferred income taxes	5,902	10,898
Long-term deferred revenue	12,240
Amortization of deferred credits	(2,928)	(3,854)
Unfavorable lease liabilities		(4,525)
Amortization of debt financing costs and accretion of interest on non-interest-bearing subordinated notes	3,182	3,147
Loss on extinguishment of debt		3,616
Loss (Gain) on disposal of assets	528	(49)
Provision for obsolete expendable parts and supplies	287	477
Loss on lease termination		9,540
Changes in assets and liabilities:
Receivables	8,462	5,903
Expendable parts and supplies	(1,403)	(5,076)
Prepaid expenses and other current assets	(1,257)	(7,861)
Accounts payable	(9,890)	(4,888)
Accrued liabilities	11,659	9,625
Change in operating lease right-of-use assets	(4,459)
Net cash provided by operating activities	103,601	114,077
Cash flows from investing activities:
Capital expenditures	(25,160)	(116,731)
Sales of investment securities		20,077
Lease and equipment deposits	(13,804)	621
Returns of lease and equipment deposits	13,850
Net cash used in investing activities	(25,114)	(96,033)
Cash flows from financing activities:
Proceeds from long-term debt	23,000	163,658
Principal payments on long-term debt and financing leases	(103,718)	(197,409)
Debt financing costs	(1,394)	(4,870)
Debt prepayment costs		(1,672)
Stock issuance costs		185
Repurchase of stock	(498)	(1,514)
Net cash used in financing activities	(82,610)	(41,622)
Net change in cash, cash equivalents and restricted cash	(4,123)	(23,578)
Cash, cash equivalents and restricted cash at beginning of period	72,501	107,134
Cash, cash equivalents and restricted cash at end of period	68,378	83,556
Supplemental cash flow information
Cash paid for interest	30,375	37,587
Cash paid for income taxes, net	45	415
Operating lease payments in operating cash flows	34,919
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange of lease liabilities	145,054
Supplemental non-cash investing activities
Accrued capital expenditures	$ 60	$ 836

Organization and Operations

9 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Operations

1.	Organization and Operations

About Mesa Air Group, Inc.

Headquartered in Phoenix, Arizona, Mesa Air Group, Inc. ("Mesa" or the "Company") is a holding company whose principal subsidiary, Mesa Airlines, Inc. ("Mesa Airlines"), operates as a regional air carrier providing scheduled flight service to 66 cities in 29 states, the District of Columbia and Mexico. As of June 30, 2020, Mesa operated a fleet of 145 aircraft with approximately 175 daily departures and 3,400 employees. Mesa operates all of its flights as either American Eagle or United Express flights pursuant to the terms of the capacity purchase agreements entered into with American Airlines, Inc. (“American”) and United Airlines, Inc. (“United”).

The financial arrangements between the Company and its major airline partners involve a revenue-guarantee arrangement (i.e., a "capacity purchase agreement") whereby the major airline pays a monthly guaranteed amount for each aircraft under contract, a fixed fee for each block hour (the number of hours during which the aircraft is in revenue service, measured from the time of gate departure before take-off until the time of gate arrival at the destination) and flight flown and reimbursement of certain direct operating expenses in exchange for providing regional flying. The major airline partners also pay certain expenses directly to suppliers, such as fuel, ground operations and landing fees. Under the terms of these capacity purchase agreements, the major airline controls route selection, pricing and seat inventories, thereby reducing the Company's exposure to fluctuations in passenger traffic, fare levels, and fuel prices.

Impact of the COVID-19 Pandemic

The unprecedented and rapid spread of COVID-19 and the related travel restrictions and social distancing measures implemented throughout the world have significantly reduced demand for air travel. The length and severity of the reduction in demand due to the pandemic remains uncertain. This reduction in demand has had an unprecedented and materially adverse impact on our revenues and financial position. The exact timing and pace of a recovery in demand is uncertain given the significant impact of the pandemic on the overall U.S. and global economy. Our forecasted expense management and liquidity measures may be modified as we clarify the demand recovery timing. Since a portion of the consideration we receive under our capacity purchase agreements is fixed, the impact to Mesa will be partially mitigated or offset. In addition, we have limited exposure to fluctuations in passenger traffic, ticket and fuel prices. While the fixed contract consideration remains mostly unchanged, the variable revenue based on number of block hours was significantly reduced beginning in the last few weeks in March and in the June 2020 quarter. We may experience further reductions in subsequent quarters. The Company further reports that, beginning in March 2020, it experienced a material decline in demand in block hours from both of its major airline partners, American and United Airlines, Inc. (“United” and together with American, the “Partners”) resulting from the spread of the COVID-19 virus. As a result of this decline in demand and the subsequent capacity reductions by the Company’s Partners, the Company operated at significantly lower block hours in the June 2020 quarter. While there has been a modest demand recovery, the Company anticipates similar schedule reductions will likely continue into the fourth quarter of 2020 and may continue throughout the remainder of calendar year 2020 and into 2021.

In response to the recent COVID-19 pandemic, we have implemented various measures to protect our employees as they continue to provide safe and reliable transportation to the passengers of American and United. The safety of our employees and passengers remains our primary focus and, to that end, measures that we have taken include but are not limited to:

▪

Increasing the scope of cleaning and sanitization of aircraft both while remaining overnight and on turn flights, including the use of Electrostatic Spraying (ESS) and the expansion of Flight Deck cleaning protocols. Both on our own, and in coordination with our codeshare partners, we have taken steps to ensure that high touch areas used by both employees and customers are routinely and comprehensively cleaned and disinfected to prevent transmission of the virus on surfaces. To assist our crewmembers in keeping the aircraft clean and disinfected, we have increased the supply of sanitizing wipes onboard.

▪

Mandated face covering for all employees working onboard aircraft, at corporate and training facilitates and locations where social distancing cannot be maintained.

▪

In coordination with our codeshare partners, we’ve implemented a policy that requires all crewmembers to wear face coverings while on duty. We have provided, and continue to resupply, our employees with Personal Protective Equipment (PPE) consisting of gloves and face coverings for use whenever social distancing cannot be maintained or when working with our customers. In addition, at various locations, we have coordinated with our codeshare partners to conduct temperature checks of employees reporting for duty. In those locations where this is not yet established, crewmembers have been directed to self-monitor their temperature before reporting for duty and twice daily.

▪

Based on recommendations from the Centers for Disease Control (CDC), we have increased facility cleaning and disinfection protocols at all of our facilities and have implemented social distancing measures including extending our current remote working policy for many of our Corporate personnel. We’ve enhanced current protocol to increase physical distance between workers who remain working at our Corporate facilities.

▪

Enhanced protocols that exceed CDC guidance for the handling of employees who are positive for, or suspected of, COVID-19 to ensure that they have the necessary time off. Additionally, we have implemented protocols to ensure that proper notification is made to any affected employees. Protocols have also been put into place for the immediate disinfection of any affected aircraft above and beyond routine cleaning and disinfection protocols.

▪

Offering Leaves of Absence to employees starting in May in blocks of 1-3 months.

Expense Management. With the reduction in revenue, we have, and will continue to implement cost saving initiatives, including:

▪

Reducing employee-related costs, including:

▪

Offering voluntary short-term unpaid leaves to all employees.

▪

Compensation reductions for Executive level employees.

▪

Instituting a company-wide hiring freeze.

▪

Delaying non-essential heavy maintenance expense and reducing or suspending other discretionary spending.

Balance Sheet, Cash Flow and Liquidity. As of June 30, 2020, our cash and cash equivalents balance was $64.9 million. We have taken the following actions to increase liquidity and strengthen our financial position.

▪

Reducing planned heavy engine and airframe maintenance events by approximately $16.8 million in the current fiscal year.

▪

Working with our major partners and original equipment manufacturers ("OEM") to delay the timing of our future aircraft and spare engine deliveries.

▪

Drew $23.0 million from our previously undrawn revolving credit facility with CIT Bank, N.A.

▪

In April 2020, we were granted $92.5 million in emergency relief through the payroll support program of the CARES Act to be paid in installments through September 2020. We received $46.3 million as of June 2020 and the remaining $46.2 million is scheduled to be paid to Mesa in three equal monthly payments from July to September 2020. $43.0 million has been utilized to offset the payroll expenses in the quarter ended June 30, 2020 and $3.3 million has been deferred to offset future payroll costs.

▪

The CARES Act also provides for up to $25 billion in secured loans to the airline industry. We have been allocated $277.0 million under the loan program. We are in ongoing discussions with the U.S. Department of the Treasury regarding the terms and our participation level of such a loan.

American Capacity Purchase Agreement

As of June 30, 2020, the Company operated 54 CRJ-900 aircraft for American under our American Capacity Purchase Agreement. In exchange for providing flight services under our American Capacity Purchase Agreement, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown during each month. In addition, we may also receive incentives or incur penalties based upon our operational performance, including controllable on-time departures and controllable completion percentages. American also reimburses us for certain costs on an actual basis, including passenger liability and hull insurance and aircraft property taxes, all as set forth in our American Capacity Purchase Agreement. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by American. In addition, American also provides, at no cost to us, certain ground handling and customer service functions, as well as airport-related facilities and gates at American hubs and cities where we operate.

Our American Capacity Purchase Agreement establishes utilization credits which are required to be paid if the Company does not operate at minimum levels of flight operations. In prior periods, the FAA Qualification Standards (as defined below) have negatively impacted our ability to hire pilots at a rate sufficient to support required utilization levels, and, as a result, we have issued credits to American pursuant to the terms of our American Capacity Purchase Agreement.

Our American Capacity Purchase Agreement will terminate with respect to different tranches of aircraft between 2021 and 2025, unless otherwise extended or amended. As of the date of this filing, we remain in discussions with American regarding the terms of extending the 31 aircraft that are due to expire in 2021, the 16 aircraft that are due to expire in 2022, and the 7 aircraft that expire in 2025. Our American Capacity Purchase Agreement is subject to termination prior to that date, subject to our right to cure, in various circumstances including:

▪

If either American or we become insolvent, file for bankruptcy or fail to pay our debts as they become due, the non-defaulting party may terminate the agreement;

▪

Failure by us or American to perform the covenants, conditions or provisions of our American Capacity Purchase Agreement, subject to 15 days' notice and cure rights;

▪

If we are required by the FAA or the DOT to suspend operations and we have not resumed operations within three business days, except as a result of an emergency airworthiness directive from the FAA affecting all similarly equipped aircraft, American may terminate the agreement;

▪

If our controllable flight completion factor falls below certain levels for a specified period of time, subject to our right to cure; or

▪

Upon a change in our ownership or control without the written approval of American.

In the event that American has the right to terminate our American Capacity Purchase Agreement, American may, in lieu of termination, withdraw up to an aggregate of 14 aircraft from service under our American Capacity Purchase Agreement. Upon any such withdrawal, American's payments to us would be correspondingly reduced by the number of withdrawn aircraft.

On January 31, 2019, the Company entered into an amendment to the American Capacity Purchase Agreement, the terms of which provide for new and revised operational performance metrics, the Company's right to earn additional incentive compensation based on the achievement of such metrics, and the right of American to permanently withdraw up to six (6) aircraft in the event the Company fails to meet such new/revised performance metrics. Under the terms of such amendment the Company agreed, effective April 2, 2019, to convert two (2) aircraft to be utilized by the Company as operational spares in the Company's sole discretion throughout its system. In July 2019, American exercised its right to permanently withdraw two (2) aircraft from the American Capacity Purchase Agreement due to the Company's failure to meet certain performance metrics. The aircraft were removed on November 2, 2019. On November 25, 2019, the Company amended its agreement with American Airlines. The Company did not meet certain performance metrics during the then most recent measurement period, which would have allowed American to remove two additional aircraft from the capacity purchase agreement. American had agreed to defer the right to remove these two aircraft but subsequently elected to remove one of the two previously deferred aircraft, effective January 2, 2020. As of January 2, 2020, American had removed three (3) of the six (6) aircraft under the January 31^st amendment.

On April 3, 2020, the Company received a new withdrawal notice from American seeking to permanently withdraw three aircraft from the American Capacity Purchase Agreement. Two of the aircraft were withdrawn effective May 19, 2020 and the third aircraft was withdrawn effective June 1, 2020. The withdrawal of these three aircraft stems from withdrawal rights that American previously asserted were triggered in September 2019 and November 2019. At such time, American refrained from exercising such withdrawal rights, however, reserved the right to withdraw the three aircraft at a later date under certain circumstances. In light of the rapid grounding of aircraft caused by the COVID-19 virus, the overall reduction in demand for air travel, and the need to reduce capacity, American elected to remove such aircraft in early June.

On June 11, 2020, the Company entered into the Twenty-First Amendment to The American Capacity Purchase Agreement effective April 1, 2020. The amendments include (i) the permanent withdrawal of two (2) additional aircraft from the American Capacity Purchase Agreement, effective June 15, 2020, with such aircraft included in the tranche of aircraft American has the right to ratably remove commencing January 1, 2021 in exchange for American paying the full cost of the aircraft for the same period and (ii) the addition of utilization-based credits, entitling American to payment credits for the period April 1, 2020 through September 30, 2020, based upon the achievement of agreed upon aircraft utilization thresholds, subject to Mesa’s receipt of previously approved funds under the CARES Act. The impact of the contract modification was not material to the three or nine months ended June 30, 2020.

United Capacity Purchase Agreement

As of June 30, 2020, the Company operated 20 CRJ-700 and 60 E-175 aircraft for United under our United Capacity Purchase Agreement. In exchange for providing the flight services under our United Capacity Purchase Agreement, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown and the results of passenger satisfaction surveys. United also reimburses us for certain costs on an actual basis, including property tax per aircraft and passenger liability insurance. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by United. Under our United Capacity Purchase Agreement, United owns 42 of the 60 E-175 aircraft and leases them to us at nominal amounts. United reimburses us on a pass-through basis for all costs related to heavy airframe and engine maintenance, landing gear, auxiliary power units ("APUs") and component maintenance for the 42 E-175 aircraft owned by United. Our United Capacity Purchase Agreement permits United, subject to certain conditions, including the payment of certain costs tied to aircraft type, to terminate the agreement in its discretion, or remove aircraft from service, by giving us notice of 90 days or more. If United elects to terminate our United Capacity Purchase Agreement in its entirety or permanently remove select aircraft from service, we are permitted to return any of the affected E-175 aircraft leased from United at no cost to us. In addition, if United removes any of our 18 owned E-175 aircraft from service at its direction, United would remain obligated to assume the aircraft ownership and associated debt with respect to such aircraft through the end of the term of the agreement.

On November 26, 2019, we amended and restated our United Capacity Purchase Agreement to, among other things, incorporate the terms of the 14 prior amendments to that Agreement and to extend the term thereof through the addition of twenty (20) new Embraer E175LL aircraft to the scope of such Agreement. These new aircraft will be financed and owned by us and operated for a period of twelve (12) years from the in-service date. Deliveries of the new E175LL aircraft were scheduled to begin in May 2020 and be completed by December 31, 2020. In March 2020, the deliveries of the new E175LL aircraft were negotiated between United and Embraer to begin in September 2020 and be completed by the quarter ended June 30, 2021. Commencing five (5) years after the actual in-service date, United has the right to remove the E175LL aircraft from service by giving us notice of 90 days or more, subject to certain conditions, including the payment of certain wind-down expenses plus, if removed prior to the ten (10) year anniversary of the in-service date, certain accelerated margin payments.

In addition to adding the 20 new E175LL aircraft to the amended and restated United Capacity Purchase Agreement, we extended the term of our 42 E-175 aircraft leased from United for an additional five (5) years, which now expire between 2024 and 2028. As part of the amended and restated United Capacity Purchase Agreement, we agreed to lease our CRJ-700 aircraft to another United Express service provider for a term of seven (7) years. We will continue to operate such aircraft until they are transitioned to the new service provider. United has a right to purchase the CRJ-700 aircraft at the then fair market value. In addition, we own 18 E-175 aircraft that expire in 2028.

Our United Capacity Purchase Agreement is subject to early termination under various circumstances noted above and including:

▪

By United if certain operational performance factors fall below a specified percentage for a specified time, subject to notice under certain circumstances;

▪

By United if we fail to perform the material covenants, agreements, terms or conditions of our United Capacity Purchase Agreement or similar agreements with United, subject to thirty (30) days' notice and cure rights;

▪

If either United or we become insolvent, file bankruptcy or fail to pay debts when due, the non-defaulting party may terminate the agreement; or

▪

By United if we merge with, or if control of us is acquired by another air carrier or a corporation directly or indirectly owning or controlling another air carrier.

Summary of Significant Accounting Policies

9 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation.

These condensed consolidated financial statements should be read in conjunction with, the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2019 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2019 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented.

The Company is an "emerging growth company," as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act") and may remain an emerging growth company until the last day of its fiscal year following the fifth anniversary of its August 2018 IPO, subject to specified conditions. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to "opt out" of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

Adoption of New Lease Standard

Effective October 1, 2019, we have adopted ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02") which provides guidance requiring lessees to recognize a right-of-use asset and a lease liability on the balance sheet for substantially all leases, with the exception of short-term leases. Leases will be classified as either financing or operating, with classification affecting the pattern of expense recognition in the statement of income. We determine if an arrangement is a lease at inception. Our current lease activities are recorded in operating lease right-of-use (“ROU”) assets, current maturities of operating lease and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are included in property and equipment, net, current portion of long-term debt and financing leases, long-term debt and financing leases, excluding current portion.

ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

As a lessee, we elected a short-term lease exception policy on all classes of underlying assets, permitting us to not apply the recognition requirements of this standard to short-term leases (i.e. leases with terms of 12 months or less).

As a lessor, our capacity purchase agreements identify the "right of use" of a specific type and number of aircraft over a stated period-of-time. A portion of the compensation in the capacity purchase agreements are designed to reimburse the Company for certain aircraft ownership costs of these aircraft. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices.

Aircraft Leases

In addition to the aircraft we lease from United under our United Capacity Purchase Agreement, approximately 12% of our aircraft are leased from third parties. All of our aircraft leases have been classified as operating leases, which results in rental payments being charged to expense over the term of the related leases. In the event that we or one of our major airline partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities will be written off.

The majority of the Company's leased aircraft are leased through trusts that have a sole purpose to purchase, finance, and lease these aircraft to the Company; therefore, they meet the criteria of a variable interest entity. However, since these are single-owner trusts in which the Company does not participate, the Company is not at risk for losses and is not considered the primary beneficiary. Management believes that the Company's maximum exposure under these leases is the remaining lease payments.

Contract Liabilities

Contract liabilities consist of deferred credits for cost reimbursements from major airline partners related to aircraft modifications associated with capacity purchase agreements and pilot training. The deferred credits are recognized over time depicting the pattern of transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements.

Current and non-current deferred credits are recorded to other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. The Company's total current and non-current deferred credit balances at June 30, 2020 and September 30, 2019 are $9.4 million and $12.1 million, respectively. The Company recognized $0.9 million and $1.3 million of the deferred credits to revenue in the condensed consolidated statements of operations during the three months ended June 30, 2020 and 2019, respectively, and $2.9 million and $3.8 million during the nine months ended June 30, 2020 and 2019, respectively.

Contract Assets

The Company recognizes assets from the costs incurred to fulfill a contract including aircraft painting and reconfiguration and flight service personnel training costs. These costs are amortized based on the pattern of transfer of the services in relation to flight hours over the term of the contract. Contract assets are recorded as other assets in the condensed consolidated balance sheets. The Company's contract assets balances at June 30, 2020 and September 30, 2019 are $2.4 million and $3.9 million, respectively. Contract cost amortization was $0.3 million and $0.6 million for the three months ended June 30, 2020 and 2019, respectively, and $1.2 million and $1.8 million for the nine months ended June 30, 2020 and 2019, respectively.

Use of Estimates

The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates.

Maintenance Expense

The Company operates under a Federal Aviation Administration ("FAA") approved continuous inspection and maintenance program. The Company uses the direct expense method of accounting for its maintenance of regional jet engine overhauls, airframe, landing gear, and normal recurring maintenance wherein the Company recognizes the expense when the maintenance work is completed, or over the repair period, if materially different. Our maintenance policy is determined by fleet when major maintenance is incurred. For leased aircraft, the Company is subject to lease return provisions that require a minimum portion of the "life" of an overhaul be remaining on the engine at the lease return date. The Company estimates the cost of maintenance lease return obligations and accrues such costs over the remaining lease term when the expense is probable and can be reasonably estimated.

Under the Company's aircraft operating lease agreements and FAA operating regulations, it is obligated to perform all required maintenance activities on its fleet, including component repairs, scheduled air frame checks and major engine restoration events. The Company estimates the timing of the next major maintenance event based on assumptions including estimated usage, FAA-mandated maintenance intervals and average removal times as recommended by the manufacturer. The timing and the cost of maintenance are based on estimates, which can be impacted by changes in utilization of its aircraft, changes in government regulations and suggested manufacturer maintenance intervals. Major maintenance events consist of overhauls to major components.

Engine overhaul expense totaled $3.2 million and $11.4 million for the three months ended June 30, 2020, and 2019, respectively, of which $0.4 million and $1.9 million, respectively, was pass-through expense. Engine overhaul expense totaled $28.3 million and $20.8 million for the nine months ended June 30, 2020, and 2019, respectively, of which $3.0 million and $3.0 million, respectively, was pass-through expense. Airframe C-check expense totaled $2.9 million and $4.4 million for the three months ended June 30, 2020, and 2019, respectively, of which $0.8 million and $0.0 million, respectively, was pass-through expense. Airframe C-check expense totaled $20.6 million and $10.6 million for the nine months ended June 30, 2020, and 2019, respectively, of which $5.9 million and $0.0 million, respectively, was pass-through expense.

Contract Revenue and Pass- Through and Other

9 Months Ended

Jun. 30, 2020

Revenue From Contract With Customer [Abstract]

Contract Revenue and Pass- Through and Other

3.	Contract revenue and Pass- through and other

The Company recognizes contract revenue when the service is provided under its capacity purchase agreements. Under the capacity purchase agreements, our airline partners generally pay for each departure, flight hour (measured from takeoff to landing, excluding taxi time) or block hour (measured from takeoff to landing, including taxi time) incurred, and an amount per aircraft in service each month with additional incentives based on flight completion and on-time performance. The major airline partners also directly pay for or reimburses the Company for certain direct expenses incurred under the capacity purchase agreement, such as fuel and airport landing fees. The Company’s performance obligation is met when each flight is completed and revenue is recognized and reflected in contract revenue. The directly reimbursed expenses, earned as flights are completed over the agreement term, are recognized and reflected in pass-through revenue.

During the quarter ended June 30, 2020, the Company completed a significantly lower than normal number of flights due to the impact of COVID-19. Since the revenue recognition is based on the number of flights completed, the fixed amount of cash received exceeded the revenue recognized based on the number of flights completed during the quarter. Under US GAAP, the fixed monthly payments are recognized as revenue ratably based on completed flights over the contract term. The Company deferred $16.0 million of revenue in the quarter ended June 30, 2020. The current portion of $3.8 million of deferred revenue is recorded as a part of other accrued expenses and long-term portion of $12.2 million is recorded as deferred revenue on the balance sheet. This deferred revenue will be recognized when flights are completed over the remaining contract term.

The deferred revenue balance as of June 30, 2020 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (In thousands):

	Total Revenue
2020	$	—
2021		7,397
2022		8,603
Total	$	16,000

A portion of the Company's compensation under its capacity purchase agreements with American and United is designed to reimburse the Company for certain aircraft ownership costs. The Company has concluded that a component of its revenue under these agreements is deemed to be lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period-of-time.

The lease revenue associated with the Company's capacity purchase agreements is accounted for as an operating lease and is reflected as contract revenue on the Company's condensed consolidated statements of operations. The Company recognized $52.0 million and $54.5 million of lease revenue for the three months ended June 30, 2020 and 2019, respectively, and $157.7 million and $164.5 million of lease revenue for the nine months ended June 30, 2020 and 2019, respectively. The Company has not separately stated aircraft rental income and aircraft rental expense in the condensed consolidated statements of operations because the use of the aircraft is not a separate activity of the total service provided under our capacity purchase agreements.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Recent Accounting Pronouncements

9 Months Ended

Jun. 30, 2020

Accounting Changes And Error Corrections [Abstract]

Recent Accounting Pronouncements

4.	Recent Accounting Pronouncements

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) (“ASU2020-04”). This ASU provides optional expedients and exceptions for a limited period of time for accounting for contracts, hedging relationships, and other transactions affected by the London Interbank Offered Rate (LIBOR) or another reference rate expected to be discontinued. Optional expedients can be applied from March 12, 2020 through December 31, 2022. We are currently evaluating the impact that the new guidance will have on our consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"). This ASU introduces a new accounting model known as Credit Expected Credit Losses (“CECL”). CECL requires earlier recognition of credit losses, while also providing additional transparency about credit risk. The CECL model utilizes a lifetime expected credit loss measurement objective for the recognition of credit losses for receivables at the time the financial asset is originated or acquired. The expected credit losses are adjusted each period for changes in expected lifetime credit losses. This model replaces the multiple existing impairment models in current GAAP, which generally require that a loss be incurred before it is recognized. The new standard will also apply to receivables arising from revenue transactions such as contract assets and accounts receivables. There are other provisions within the standard affecting how impairments of other financial assets may be recorded and presented, as well as expanded disclosures. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which provides guidance requiring lessees to recognize a right-of-use asset and a lease liability on the balance sheet for substantially all leases, with the exception of short-term leases. Leases will be classified as either financing or operating, with classification affecting the pattern of expense recognition in the statement of income. The Company adopted Topic 842 effective October 1, 2019 and elected the package of transition practical expedients for expired or existing contracts, which does not require reassessment of: (1) whether any of the Company’s contracts are or contain leases, (2) lease classification and (3) initial direct costs. In July 2018, the FASB issued ASU No. 2018-11, "Targeted Improvements - Leases (Topic 842)." The Company did not elect the hindsight practical expedient. This update provides an optional transition method that allows entities to elect to apply the standard using the modified retrospective approach at its effective date, versus recasting the prior years presented. If this adoption method is elected, an entity would recognize a cumulative-effect adjustment to the opening balance of retained earnings in the year of adoption. The Company elected this adoption method on October 1, 2019.There was no adjustment to retained earnings.

Additionally, the Company’s adoption of Topic 842 did not have a significant impact on the recognition, measurement or presentation of lease revenue and lease expenses within the consolidated statements of operations or the consolidated statements of cash flows. The Company’s adoption of Topic 842 did not have a material impact on the timing or amount of the Company’s lease revenue as a lessor. The Company’s prepaid aircraft rents, accrued aircraft rents and deferred rent credits that were separately stated in the Company’s September 30, 2019 balance sheet have been classified as a component of the Company’s right-of-use assets effective October 1, 2019. The consolidated financial statements for the three months ended December 31, 2019 are presented under the new standard, while comparative years presented are not adjusted and continue to be reported in accordance with the Company’s historical accounting policy. See Note 15, "Leases, Commitments and Contingencies," for more information.

In July 2018, the FASB issued ASU 2018-09, Codification Improvements, which contains amendments that affect a wide variety of Topics in the Codification, including amendment to Subtopic 718-40, Compensation-Stock Compensation-Income Taxes, that clarifies the timing of when an entity should recognize excess tax benefits. We adopted this standard on October 1, 2019 and it did not have a material impact on our condensed consolidated financial statements.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

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+ Details

Concentrations

9 Months Ended

Jun. 30, 2020

Risks And Uncertainties [Abstract]

Concentrations

5.	Concentrations

At June 30, 2020, the Company had capacity purchase agreements with American and United. All of the Company's condensed consolidated revenue for the nine months ended June 30, 2020 and 2019 and accounts receivable at June 30, 2020 and September 30, 2019 was derived from these agreements. The terms of both the American and United capacity purchase agreements are not aligned with the lease obligations on the aircraft performing services under such agreements.

Amounts billed by the Company under capacity purchase agreements are subject to the Company's interpretation of the applicable capacity purchase agreement and are subject to audit by the Company's major airline partners. Periodically, the Company's major airline partners dispute amounts billed and pay amounts less than the amount billed. Ultimate collection of the remaining amounts not only depends upon the Company prevailing under the applicable audit, but also upon the financial well-being of the major airline partner. As such, the Company periodically reviews amounts past due and records a reserve for amounts estimated to be uncollectible. The allowance for doubtful accounts was $5.4 million and $1.0 million at June 30, 2020 and September 30, 2019, respectively. If the Company's ability to collect these receivables and the financial viability of its partners is materially different than estimated, the Company's estimate of the allowance could be materially impacted.

American accounted for approximately 60% and 53% of the Company's total revenue for the three months ended June 30, 2020 and 2019, respectively, and 53 % and 54 % for the nine months ended June 30, 2020 and 2019, respectively. United accounted for approximately 40% and 47% of the Company's revenue for the three months ended June 30, 2020 and 2019, respectively, and 47% and 46% for the nine months ended June 30, 2020 and 2019, respectively. A termination of either the American or the United capacity purchase agreement would have a material adverse effect on the Company's business prospects, financial condition, results of operations, and cash flows.

Intangible Assets

9 Months Ended

Jun. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

6.	Intangible Assets

The Company monitors for any indicators of impairment of the intangible assets. When certain conditions or changes in the economic situation such as the current environment brought by COVID-19 exist, the assets may be impaired and the carrying amount of the assets exceed its fair value.

We determined that our reduced flying schedules and cash flow projections as a result of the COVID-19 pandemic indicate that an impairment loss may have been incurred. Therefore, we quantitatively assessed whether it was more likely than not that the intangible assets we hold have been impaired as of June 30, 2020. We reviewed our previous forecasts and assumptions based on our current projections that are subject to various risks and uncertainties, including: (1) forecasted revenues, expenses and cash flows, including the duration and extent of impact to our business from the COVID-19 pandemic, (2) current discount rates, (3) changes to the regulatory environment and (4) the nature and amount of government support that will be provided.

Based on our carrying amount recoverability test, we have concluded that our finite-lived intangible assets are not impaired as of June 30, 2020. Given the uncertain future amid COVID-19, we will conduct additional tests in the 4^th quarter of 2020.

Information about the intangible assets of the Company at June 30, 2020 and September 30, 2019, were as follows (in thousands):

	June 30,			September 30,
	2020			2019
Customer relationship	$	43,800		$	43,800
Accumulated amortization		(35,393	)		(34,268	)
	$	8,407		$	9,532

Total amortization expense recognized was approximately $0.4 million and $0.5 million for the three months ended June 30, 2020 and 2019, respectively, and $1.1 million and $1.4 million for the nine months ended June 30, 2020 and 2019, respectively. The Company expects to record amortization expense of $0.4 million for the remainder of 2020, and $1.2 million, $1.0 million, $0.9 million, $0.8 million for fiscal years 2021, 2022, 2023, and 2024, respectively.

Balance Sheet Information

9 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Information

7.	Balance Sheet Information

Certain significant amounts included in the Company's condensed consolidated balance sheet as of June 30, 2020 and September 30, 2019, consisted of the following (in thousands):

	June 30,			September 30,
	2020			2019
Expendable parts and supplies, net:
Expendable parts and supplies	$	26,368		$	25,336
Less: obsolescence and other		(3,950	)		(3,999	)
	$	22,418		$	21,337

Prepaid expenses and other current assets:
Prepaid aircraft rent	$	—		$	35,786
Deferred reimbursed costs		1,387			2,092
Other		5,756			3,045
	$	7,143		$	40,923
Property and equipment, net:
Aircraft and other flight equipment	$	1,597,916		$	1,582,199
Other equipment		5,323			5,122
Leasehold improvements		2,763			2,797
Vehicles		962			924
Building		699			699
Furniture and fixtures		303			302
Total property and equipment		1,607,966			1,592,043
Less: accumulated depreciation		(374,239	)		(318,458	)
	$	1,233,727		$	1,273,585

Other accrued expenses:
Accrued property taxes	$	9,035		$	9,186
Accrued interest		5,941			4,497
Accrued vacation		5,767			6,128
Deferred revenue-current portion		3,760			—
Other		13,160			9,077
	$	37,663		$	28,888

The Company monitors for any indicators of impairment of the long-lived fixed assets. When certain conditions or changes in the economic situation such as the current environment brought by COVID-19 exist, the assets may be impaired and the carrying amount of the assets exceed its fair value. The assets need to be tested for recoverability of carrying amount.

To determine whether impairments exist, we group assets at the Capacity Purchase Agreement and fleet-type level (i.e., the lowest level for which there are identifiable cash flows) and then estimate future cash flows based on projections of capacity purchase arrangements, block hours, maintenance events, labor costs and other relevant factors. Due to our reduced flying schedules and projections of future cash flows, we evaluated each of our fleets to determine if any of the fleets are impaired.

Based on our carrying amount recoverability test, we have concluded that no fleet was impaired as of June 30, 2020 as the future cash flows exceeded the carrying value of our long-lived fixed assets. Given the uncertain future amid COVID-19, we will conduct additional tests in 4^th quarter 2020.

Depreciation expense totaled approximately $20.2 million and $19.3 million for the three months ended June 30, 2020 and 2019, respectively, and $60.5 million and $56.2 million for the nine months ended June 30, 2020 and 2019, respectively.

Prior to the Company’s adoption of Topic 842 on October 1, 2019, the Company recorded amortization of the unfavorable lease liability of approximately $1.4 million for the three months ended June 30, 2019 and $4.5 million for the nine months ended June 30, 2019 as a reduction to lease expense. Upon the Company’s adoption of Topic 842, the unfavorable lease liability is now included in its ROU asset balance and amortized therein.

Fair Value Measurements

9 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

8.	Fair Value Measurements

The carrying values reported in the condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value because of the immediate or short-term maturity of these financial instruments.

The Company's debt agreements are not traded on an active market. The Company has determined the estimated fair value of its debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable and, therefore, could be sensitive to changes in inputs. The Company utilizes the discounted cash flow method to estimate the fair value of Level 3 debt.

The carrying value and estimated fair value of the Company's long-term debt, including current maturities, were as follows (in millions):

	Jun 30, 2020				September 30, 2019
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
Long-term debt and financing leases, including current maturities(1)	$	777.8	$	857.2	$	858.1	$	882.7

(1)

Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Long-Term Debt, Financing Leases and Other Borrowings

9 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Long-Term Debt, Financing Leases and Other Borrowings

9.	Long-Term Debt, Financing Leases and Other Borrowings

Long-term debt as of June 30, 2020 and September 30, 2019, consisted of the following (in thousands):

	June 30,			September 30,
	2020			2019
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2022⁽¹⁾⁽²⁾	$	41,472		$	49,795
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2024⁽³⁾		55,674			60,761
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2027⁽⁴⁾		105,786			110,912
Notes payable to secured parties, collateralized by the underlying
aircraft, due 2028⁽⁵⁾		181,776			191,168
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2028⁽⁶⁾		141,871			152,945
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2022⁽⁷⁾		53,647			71,998
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2022⁽⁸⁾		34,607			47,309
Notes payable to financial institution, collateralized by the underlying
equipment, due 2020⁽⁹⁾		415			1,659
Notes payable to financial institution due 2020⁽¹⁰⁾		1,523			2,329
Notes payable to financial institution, collateralized by the underlying
equipment, due 2022⁽¹¹⁾		4,182			6,962
Other obligations due to financial institution, collateralized by the underlying
equipment, due 2023⁽¹²⁾		7,196			8,530
Notes payable to financial institution, collateralized by the underlying
equipment, due 2024⁽¹³⁾		67,631			80,153
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2023⁽¹⁴⁾		52,500			65,625
Notes payable to financial institution, collateralized by the underlying
equipment, due 2023⁽¹⁵⁾		6,500			8,000
Working capital draw loan, used to cover operational needs ⁽¹⁶⁾		23,000			—
Gross long-term debt, including current maturities		777,780			858,145
Less unamortized debt issuance costs		(14,007	)		(14,822	)
Net long-term debt, including current maturities		763,773			843,323
Less current portion		(176,896	)		(165,900	)
Net long-term debt	$	586,877		$	677,423

⁽¹⁾	In fiscal 2007, the Company financed three CRJ-900 and three CRJ-700 aircraft for $120.3 million. The debt bears interest at the monthly LIBOR plus 2.25% (2.41% at June 30, 2020) and requires monthly principal and interest payments.

⁽²⁾

In fiscal 2014, the Company financed ten CRJ-900 aircraft for $88.4 million. The debt bears interest at the monthly LIBOR plus a spread ranging from 1.95% to 7.25% (2.11% to 7.41% at June 30, 2020) and requires monthly principal and interest payments. In fiscal 2018, the Company repaid $40.0 million related to four CRJ-900 aircraft.

⁽³⁾	In fiscal 2014, the Company financed eight CRJ-900 aircraft with $114.5 million in debt. The debt bears interest at 5.00% and requires monthly principal and interest payments.

⁽⁴⁾

In fiscal 2015, the Company financed seven CRJ-900 aircraft with $170.2 million in debt. The senior notes payable of $151.0 million bear interest at monthly LIBOR plus 2.71% (2.87% at June 30, 2020) and require monthly principal and interest payments. The subordinated notes payable is noninterest-bearing and become payable in full on the last day of the term of the notes. The Company has imputed an interest rate of 6.25% on the subordinated notes payable and recorded a related discount of $8.1 million, which is being accreted to interest expense over the term of the notes.

⁽⁵⁾	In fiscal 2016, the Company financed ten E-175 aircraft with $246.0 million in debt under an EETC financing arrangement (see discussion below). The debt bears interest ranging from 4.75% to 6.25% and requires semi-annual principal and interest payments.

⁽⁶⁾

In fiscal 2016, the Company financed eight E-175 aircraft with $195.3 million in debt. The senior notes payable of $172.0 million bear interest at the three-month LIBOR plus a spread ranging from 2.20% to 2.32% (2.50% to 2.62% at June 30, 2020) and require quarterly principal and interest payments. The subordinated notes payable bear interest at 4.50% and require quarterly principal and interest payments.

⁽⁷⁾

In June 2018, the Company refinanced six CRJ-900 aircraft with $27.5 million in debt and financed nine CRJ-900 aircraft, which were previously leased, with $69.6 million in debt. The senior notes payable of $65.8 million bear interest at the three-month LIBOR plus 3.50% (3.8% at June 30, 2020) and require quarterly principal and interest payments. The subordinated notes payable of $29.8 million bear interest at three month LIBOR plus 7.50% (7.8% at June 30, 2020) and require quarterly principal and interest payments.

⁽⁸⁾

InDecember 2017, the Company refinanced nine CRJ-900 aircraft with $74.9 million in debt. The senior notes payable of $46.9 million bear interest at the three-month LIBOR plus 3.50% (3.8% at June 30, 2020) and require quarterly principal and interest payments. The subordinated notes payable bear interest at the three-month LIBOR plus 4.50% (4.8% at June 30, 2020) and require quarterly principal and interest payments.

⁽⁹⁾	In fiscal 2015, the Company financed certain flight equipment with $8.3 million in debt. The debt bears interest at 5.163% and requires monthly principal and interest payments.

⁽¹⁰⁾	In fiscal 2015 and 2016, the Company financed certain flight equipment maintenance costs with $10.2 million in debt. The debt bears interest at the three-month LIBOR plus 3.07% (3.37% at June 30, 2020) and requires quarterly principal and interest payments.

⁽¹¹⁾

In fiscal 2016-2019, the Company financed certain flight equipment maintenance costs with $26.1 million in debt. The debt bears interest at the three-month LIBOR plus a spread ranging from 2.93% to 3.21% (3.23% to 3.51% at June 30, 2020) and requires quarterly principal and interest payments. The debt is subject to a fixed charge ratio covenant. As of June 30, 2020, the Company was in compliance with this covenant.

¹²⁾	In February 2018, the Company leased two spare engines. The leases were determined to be capital as the leases contain a bargain purchase option at the end of the term. Imputed interest is 9.128% and the leases requires monthly payments.

⁽¹³⁾	In January 2019, the Company financed certain flight equipment with $91.2 million in debt. The debt bears interest at the monthly LIBOR plus 3.10% (3.26% at June 30, 2020) and requires monthly principal and interest payments.

⁽¹⁴⁾

In June 2019, the Company financed ten CRJ-700 aircraft with $70.0 million in debt, which were previously leased. The debt bears interest at the monthly LIBOR plus 5.00% (5.16% at June 30, 2020) and requires monthly principal and interest payments. The interest rate reduced from 5.25% to 5.00% in 1^st quarter, 2020 due to United Airlines extension of CRJ-700.

⁽¹⁵⁾

On September 27,2019, the Company financed certain flight equipment for $8.0 million. The debt bears interest at the monthly LIBOR plus 5.00% (5.16% at June 30, 2020) and requires monthly principal and interest payments. The interest rate reduced from 5.25% to 5.00% in 1^st quarter, 2020 due to United Airlines extension of CRJ-700.

⁽¹⁶⁾

On September 25, 2019, the company extended the term on their $35.0 million working capital draw loan by three years, which now terminates in September 2022. Interest is assessed on drawn amounts at one-month LIBOR plus 3.75%. In 2^nd quarter, 2020, $23.0 million was drawn to cover operational needs.

Principal maturities of long-term debt as of June 30, 2020, and for each of the next five years are as follows (in thousands):

Periods Ending June 30,	Total Principal
Remainder of 2020	$	178,459
2021		162,494
2022		133,663
2023		79,268
2024		55,677
Thereafter		168,219
	$	777,780

The net book value of collateralized aircraft and equipment as of June 30, 2020 was $1,114.0 million.

In December 2015, an Enhanced Equipment Trust Certificate ("EETC") pass-through trust was created to issue pass-through certificates to obtain financing for new E-175 aircraft. At June 30, 2020 Mesa has $181.8 million of equipment notes outstanding issued under the EETC financing included in long-term debt on the condensed consolidated balance sheets. The structure of the EETC financing consists of a pass-through trust created by Mesa to issue pass-through certificates, which represent fractional undivided interests in the pass-through trust and are not obligations of Mesa.

The proceeds of the issuance of the pass-through certificates were used to purchase equipment notes which were issued by Mesa and secured by its aircraft. The payment obligations under the equipment notes are those of Mesa. Proceeds received from the sale of pass-through certificates were initially held by a depositary in escrow for the benefit of the certificate holders until Mesa issued equipment notes to the trust, which purchased such notes with a portion of the escrowed funds.

Mesa evaluated whether the pass-through trust formed for its EETC financing is a Variable Interest Entity ("VIE") and required to be consolidated. The pass-through trust was determined to be a VIE, however, the Company has determined that it does not have a variable interest in the pass-through trust, and therefore, has not consolidated the pass-through trust with its financial statements.

On January 28, 2019, the Company entered into a Term Loan Agreement (the "Term Loan") pursuant to which the lenders thereunder committed to lend to the Company term loans in the aggregate principal amount of $91.2 million. Borrowings under the Term Loan bear interest at LIBOR plus 3.10%. This interest rate is significantly lower than the interest rate under the Company's Spare Engine Facility (defined below), which the Term Loan refinanced and replaced. The Spare Engine Facility accrued interest at LIBOR plus 7.25%. The Term Loan has a term of five years, with principal and interest payments due monthly over the term of the loan in accordance with an amortization schedule. The Company recorded a loss on extinguishment of debt of $3.6 million, due to a $1.9 million write-off of financing fees and $1.7 million in prepayment penalties, in connection with the repayment of the Spare Engine Facility.

On June 14, 2019, the Company completed the purchase of ten CRJ-700 aircraft, which were previously leased under the aircraft lease facility with Wells Fargo Bank Northwest, National Association, as owner trustee and lessor (the “GECAS Lease Facility”), for $70.0 million. The Company financed the aircraft purchase with $70.0 million in new debt. The notes payable of $70.0 million require monthly payments of principal and interest through fiscal 2023 bearing interest at LIBOR plus 5.0%. The Company recorded non-cash lease termination expense of $9.5 million in connection with the lease buyout.

On September 25, 2019, the Company extended the term on its $35.0 million working capital draw loan by three years, which now terminates in September 2022. Interest is assessed on drawn amounts at one-month LIBOR plus 3.75%. In the 2^nd quarter of 2020, $23.0 million was drawn to cover operational needs.

On September 27, 2019, the Company financed certain flight equipment with $8.0 million in new debt. This debt requires monthly payments of principal and interest through fiscal 2023 and bears interest at Libor plus 5.0%.

On April 9, 2020, Export Development Canada (“EDC”) provided Mesa Air with deferral of principle payments due and owing beginning on March 19, 2020 to and including September 30, 2020 totaling $28.0 million. All Deferred Payments shall be due in a lump sum payment on September 30, 2020 per the letter agreement dated April 9, 2020. The company performed the debt modification accounting assessment and treated as a modification with immaterial issuance costs capitalized.

In June 2020, the company amended their RASPRO aircraft lease agreement to defer $4.0 million of a lease payment otherwise due in June 2020. Per the amended agreement dated June 5,2020, the company is to pay this amount over the period of September 2021 through March 2024. The company made the accounting election available for COVID-19 related concession provided by a lessor. This event is not a lease modification and requires no changes to current accounting treatment.

Earnings Per Share and Equity

9 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Earnings Per Share and Equity

10.	Earnings Per Share and Equity

Calculations of net income per common share attributable to Mesa Air Group were as follows (in thousands, except per share data):

	Three Months Ended June 30,				Nine Months Ended June 30,
	2020		2019		2020		2019
Net income attributable to Mesa Air Group	$	3,419	$	3,007	$	16,089	$	35,337
Basic weighted average common shares outstanding		35,299		34,835		35,154		34,683
Add: Incremental shares for: (1)
Dilutive effect of restricted stock		—		277		94		368
Diluted weighted average common shares outstanding		35,299		35,112		35,248		35,051
Net income per common share attributable to Mesa Air Group:
Basic	$	0.10	$	0.09	$	0.46	$	1.02
Diluted	$	0.10	$	0.09	$	0.46	$	1.01

Basic income per common share is computed by dividing net income attributable to Mesa Air Group by the weighted average number of common shares outstanding during the period.

The number of incremental shares from the assumed issuance of shares relating to restricted stock and exercise of warrants (excluding warrants with a nominal conversion price) is calculated by applying the treasury stock method. Share-based awards and warrants whose impact is considered to be anti-dilutive under the treasury stock method were excluded from the diluted net income or loss per share calculation. In loss periods, these incremental shares are excluded from the calculation of diluted loss per share, as the inclusion of unvested restricted stock and warrants would have an anti-dilutive effect. There were no anti-dilutive shares relating to restricted stock and exercise of warrants that were excluded from the calculation of diluted loss per share for the three and nine months ended June 30, 2020 and 2019.

Common Stock

9 Months Ended

Jun. 30, 2020

Stockholders Equity Note [Abstract]

Common Stock

11.	Common Stock

The Company previously issued warrants to third parties, which had a five-year term to be converted to common stock at an exercise price of $0.004 per share. Certain persons who are not U.S. citizens held outstanding warrants to purchase shares of the Company's common stock. The warrants were exercisable only if consistent with federal law, which requires that no more than 24.9% of the Company's stock be voted, directly or indirectly, or controlled by persons who are not U.S. citizens. The warrants could be exercised upon the warrant holders demonstrating U.S. citizenship or if consistent with above described federal law ownership limitations. In June 2018, the Company and holders agreed to extend the term of outstanding warrants set to expire by five years (through fiscal year 2023). As of March 31, 2020, all the outstanding warrants had been fully exercised.

In July 2018, the Company's Board of Directors and Compensation Committee approved the issuance of shares of restricted common stock under its 2018 Equity Incentive Plan (the "2018 Plan") immediately following completion of the Company's IPO to certain of its employees and directors in exchange for the cancellation of existing restricted phantom stock units, unvested restricted shares and SARs. The shares of restricted common stock issued under the 2018 Plan in exchange for the cancellation of restricted phantom stock units, unvested restricted shares and SARs are subject to vesting on the same terms set forth in the prior vesting schedules and are not subject to acceleration in connection with the 2018 Plan issuances.

On August 8, 2018, the Company filed its Second Amended and Restated Articles of Incorporation, which, among other things: (i) effected a 2.5-for-1 stock split of its common stock; and (ii) increased the authorized number of shares of its common and preferred stock to 125,000,000 and 5,000,000, respectively. All references to share and per share amounts in the Company's condensed consolidated financial statements have been retrospectively revised to reflect the stock split and increase in authorized shares.

The Company's shares of common stock were listed on The NASDAQ Global Select Market under the symbol "MESA" effective August 10, 2018. On August 14, 2018, the Company completed its IPO, in which it issued and sold 9,630,000 shares of common stock, no par value, at a public offering price of $12.00 per share (the "Firm Shares"). Additionally, in connection with the IPO, the Company granted the underwriters an option to purchase up to an additional 1,444,500 shares of common stock at the same price. On September 11, 2018, the Company closed the sale of 1,344,500 shares ("Option Shares") of its common stock, in connection with the partial exercise of the overallotment option granted to the underwriters in its IPO. Of the 1,344,500 Option Shares sold, 723,985 were purchased directly from the Company and the remaining 620,515 shares were purchased directly from the selling shareholders. The Firm Shares and Option Shares were sold to the public for a price of $12.00 per share. The aggregate gross proceeds to us from the IPO were approximately $124.2 million. The Company received $111.7 million in net proceeds after deducting $8.7 million of underwriting discounts and commissions and $3.6 million in offering costs.

On April 9, 2019, and pursuant to Section 4.4 of the 2018 Plan in connection with the 2.5-for-1 stock split effected on August 8, 2018, the board of directors approved an increase in the number of shares authorized for issuance under the 2018 Plan by 1,000,000 shares of common stock.

The Company has not historically paid dividends on shares of its common stock. Additionally, the Company's aircraft lease facility (the "RASPRO" Lease Facility) with RASPRO Trust 2005, a pass-through trust contains restrictions that limit the Company's ability to or prohibit it from paying dividends to holders of its common stock.

Income Taxes

9 Months Ended

Jun. 30, 2020

Income Tax Disclosure [Abstract]

Income Taxes

12.	Income Taxes

The Company’s effective tax rate (ETR) from continuing operations was 30.7% and 28.3% for the three months and nine months ended June 30, 2020, respectively, and 22.2% and 23.6% for the three months and nine months ended June 30, 2019, respectively. The Company's ETR during the three months and nine months ended June 30, 2020 was different from the prior year tax rates as a result of differences in the book and tax value of the vesting and exercise of stock compensation, state taxes, and changes in valuation allowance against state net operating losses, as well as differences between the book and tax deductions associated with meals, entertainment, employer provided parking, and compensation of officers. The non-deductible amounts related to these items increased slightly from the prior year to the current year.

The Company's ETR during the nine months ended June 30, 2019 was different than the statutory rate as a result of state taxes, the vesting and exercises of stock compensation, differences in the GAAP and tax deductibility of meals and parking benefits, and changes in the valuation allowance against state net operating losses.

As of September 30, 2019, the Company had aggregate federal and state net operating loss carryovers of approximately $478.3 million and $228.3 million, respectively, which expire in fiscal years 2027-2037 and 2020-2039, respectively. Approximately $2.7 million of state net operating loss carryforwards are expected to expire in the current fiscal year.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Share-Based Compensation and Stock Repurchases

9 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation and Stock Repurchases

13.	Share-Based Compensation and Stock Repurchases

Restricted Stock

The restricted share activity for the nine months ended June 30, 2020 were summarized as follows:

				Weighted-
				Average
	Number			Grant Date
	of Shares			Fair Value
Restricted shares unvested at September 30, 2019		847,974		$	9.56
Granted		660,297			4.07
Vested		(468,697	)		9.69
Forfeited		(6,000	)		7.03
Restricted shares unvested at June 30, 2020		1,033,574		$	6.01

As of June 30, 2020, there was $5.0 million of total unrecognized compensation cost related to unvested share-based compensation arrangements. That cost is expected to be recognized over a weighted-average period of 2.4 years.

Compensation cost for share-based awards are recognized on a straight-line basis over the vesting period. Share-based compensation expense for the three months ended June 30, 2020 and 2019 was $1.0 million and $1.5 million, respectively, and for the nine months ended June 30, 2020 and 2019 was $3.5 million and $4.3 million, respectively.

The Company repurchased 112,587 shares of its common stock for $0.5 million to cover the income tax obligation on vested employee equity awards and warrant exercises during the nine months ended June 30, 2020.

The Company has granted restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) as part of its long-term incentive compensation to employees and non-employee members of the Board of Directors. RSAs and RSUs generally vest over a period of 3 to 5 years for employees and over one year for members of the Board of Directors. The restricted common stock underlying RSAs are deemed issued and outstanding upon grant and carry the same voting rights of unrestricted outstanding common stock. The restricted common stock underlying RSUs are not deemed issued or outstanding upon grant, and do not carry any voting rights.

Employee Stock Purchase Plan

9 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Employee Stock Purchase Plan

14.	Employee Stock Purchase Plan

2019 ESPP

The Mesa Air Group, Inc. 2019 Employee Stock Purchase Plan (the "2019 ESPP") is a nonqualified plan that provides eligible employees of Mesa Air Group, Inc. with an opportunity to purchase Mesa Air Group, Inc. ordinary shares through payroll deductions. Under the 2019 ESPP, eligible employees may purchase Mesa Air Group, Inc. ordinary shares through the Employee Stock Purchase Plan. Under the 2019 ESPP, eligible employees may elect to contribute 1% to 15% of their eligible compensation during each semi-annual offering period to purchase Mesa Air Group, Inc. ordinary shares at a 10% discount.

A maximum of 500,000 Mesa Air Group, Inc. ordinary shares may be issued under the 2019 ESPP. As of June 30, 2020, eligible employees purchased and the Company issued 43,934 Mesa Air Group, Inc. ordinary shares under the 2019 ESPP.

Leases and Commitments

9 Months Ended

Jun. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Leases and Commitments

15.	Leases and Commitments

Effective October 1, 2019, the Company adopted Topic 842 and recorded ROU assets and lease liabilities of $154.6 million and $141.9 million, respectively. As part of the adoption, prepaid aircraft rent, deferred rent credits and accrued aircraft rents of $35.8 million, $21.3 million and $1.8 million, respectively, were classified as a component of the Company’s ROU assets.

At June 30, 2020, the Company leased 18 aircraft, airport facilities, office space, and other property and equipment under non-cancelable operating leases. The leases require the Company to pay all taxes, maintenance, insurance, and other operating expenses. Rental expense is recognized on a straight-line basis over the lease term, net of lessor rebates and other incentives. The Company expects that, in the normal course of business, such operating leases that expire will be renewed or replaced by other leases, or the property may be purchased rather than leased. Aggregate rental expense under all operating aircraft, equipment and facility leases totaled approximately $15.6 million and $18.1 million for the three months ended June 30, 2020 and 2019, respectively, and $51.0 million and $55.9 million for the nine months ended June 30, 2020 and 2019, respectively.

As of June 30, 2020, the Company’s operating lease right-of-use assets were $131.5 million, the Company’s current maturities of operating lease liabilities were $43.2 million, and the Company’s noncurrent lease liabilities were $71.1 million.

As of June 30, 2020, the Company’s operating lease payments in operating cash flows for the nine months ended June 30, 2020 is $34.9 million. The disclosure is not applicable for the nine months ended June 30, 2019 due to the method of adoption of the new leasing Standard ASC-842.⁽¹⁾

The table below presents lease related terms and discount rates as of June 30, 2020:

As of June 30, 2020

Weighted average remaining lease term Operating

leases

3.8 years

Weighted average discount rate Operating leases

4.2

	Three Months Ended June 30,
	2020		2019		$ Change			% Change
Operating lease cost	$	15,634	$	18,094	$	(2,460	)		(13.6	)%


	Nine Months Ended June 30,
	2020		2019		$ Change			% Change
Operating lease cost	$	51,000	$	55,897	$	(4,897	)		(8.8	)%

The following table summarizes future minimum rental payments primarily related to leased aircraft required under operating leases that had initial or remaining non-cancelable lease terms as of June 30, 2020 (in thousands):

Periods Ending June 30,	Total Maturities
2020	$	9,390
2021		47,377
2022		33,216
2023		15,947
2024		14,682
Thereafter		1,654
Less: Interest	$	(7,892	)
Amounts recorded in the Consolidated Balance Sheet	$	114,374

The following represents future minimum lease obligations under non-cancelable operating leases as of September 30, 2019 (in thousands):

Periods Ending September 30,	Total Payments
2020	$	47,814
2021		46,007
2022		31,090
2023		13,726
2024		13,185
Thereafter		1,368
Total	$	153,190

Engine Purchase Commitments

On March 26, 2020, the Company and General Electric Company (“GE”), acting through its GE-Aviation business unit, entered into (a) Amended and Restated Letter Agreement No. 13-1 (“Letter Agreement No. 13-1”), which amends and restates Letter Agreement No. 13 entered into by the parties effective December 11, 2019, and (b) Amended and Restated Letter Agreement No. 12-1 (“Letter Agreement No. 12-1” and together with Letter Agreement No. 13-1, the “Amended and Restated Letter Agreements”), which amends and restates Letter Agreement No. 12 entered into by the parties effective October 22, 2019. The Amended and Restated Letter Agreements each provide that they are effective March 20, 2020.

Under Letter Agreement No. 13-1, the Company has agreed to purchase and take delivery of 20 new spare CF34-8C5 engines. Delivery of the new spare engines will now commence in April 2021, with the final spare engine being delivered in December 2021. The parties had previously agreed to commence delivery of the new spare engines in August 2020. The payment terms for the new spare engines were also amended, with payments to now be made in four (4) separate tranches commencing in October and December 2020 and February and March 2021.

The total purchase commitment under these agreements is approximately $108.0 million.

If the Company fails to accept delivery of the spare engines when duly tendered, the Company may be assessed a minimum cancellation charge based on the engine price determined as of the date of scheduled engine delivery to the Company.

Contingencies

9 Months Ended

Jun. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Contingencies

16.	Contingencies

The Company is involved in various legal proceedings (including, but not limited to, insured claims) and FAA civil action proceedings that the Company does not believe will have a material adverse effect upon its business, financial condition, or results of operations, although no assurance can be given to the ultimate outcome of any such proceedings.

Supplemental Disclosure

9 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Elements [Abstract]

Supplemental Disclosure

17.	Supplemental Disclosure

The Company adopted ASU 2016-18 on a retrospective basis during the quarter ended December 31, 2018. The following is a reconciliation of the captions in the Condensed Consolidated Balance Sheets to the Condensed Consolidated Statements of Cash Flows (in thousands):

	June 30,		September 30,
	2020		2019
Condensed Consolidated Balance Sheets
Cash and cash equivalents	$	64,934	$	68,855
Restricted cash		3,444		3,646
Cash, cash equivalents, and restricted cash in Condensed Consolidated Statement of Cash Flows	$	68,378	$	72,501

The restricted cash balance primarily includes deposits in trust accounts to collateralize letters of credit and to fund workers' compensation claims, landing fees, and other business needs.

Subsequent Events

9 Months Ended

Jun. 30, 2020

Subsequent Events [Abstract]

Subsequent Events

18.	Subsequent Events

None.

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation. These condensed consolidated financial statements should be read in conjunction with, the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2019 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2019 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented. The Company is an "emerging growth company," as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act") and may remain an emerging growth company until the last day of its fiscal year following the fifth anniversary of its August 2018 IPO, subject to specified conditions. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to "opt out" of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.
Adoption of New Lease Standard	Adoption of New Lease Standard Effective October 1, 2019, we have adopted ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02") which provides guidance requiring lessees to recognize a right-of-use asset and a lease liability on the balance sheet for substantially all leases, with the exception of short-term leases. Leases will be classified as either financing or operating, with classification affecting the pattern of expense recognition in the statement of income. We determine if an arrangement is a lease at inception. Our current lease activities are recorded in operating lease right-of-use (“ROU”) assets, current maturities of operating lease and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are included in property and equipment, net, current portion of long-term debt and financing leases, long-term debt and financing leases, excluding current portion. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. As a lessee, we elected a short-term lease exception policy on all classes of underlying assets, permitting us to not apply the recognition requirements of this standard to short-term leases (i.e. leases with terms of 12 months or less). As a lessor, our capacity purchase agreements identify the "right of use" of a specific type and number of aircraft over a stated period-of-time. A portion of the compensation in the capacity purchase agreements are designed to reimburse the Company for certain aircraft ownership costs of these aircraft. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices.
Aircraft Leases	Aircraft Leases In addition to the aircraft we lease from United under our United Capacity Purchase Agreement, approximately 12% of our aircraft are leased from third parties. All of our aircraft leases have been classified as operating leases, which results in rental payments being charged to expense over the term of the related leases. In the event that we or one of our major airline partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities will be written off. The majority of the Company's leased aircraft are leased through trusts that have a sole purpose to purchase, finance, and lease these aircraft to the Company; therefore, they meet the criteria of a variable interest entity. However, since these are single-owner trusts in which the Company does not participate, the Company is not at risk for losses and is not considered the primary beneficiary. Management believes that the Company's maximum exposure under these leases is the remaining lease payments.
Contract Liabilities	Contract Liabilities Contract liabilities consist of deferred credits for cost reimbursements from major airline partners related to aircraft modifications associated with capacity purchase agreements and pilot training. The deferred credits are recognized over time depicting the pattern of transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements. Current and non-current deferred credits are recorded to other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. The Company's total current and non-current deferred credit balances at June 30, 2020 and September 30, 2019 are $9.4 million and $12.1 million, respectively. The Company recognized $0.9 million and $1.3 million of the deferred credits to revenue in the condensed consolidated statements of operations during the three months ended June 30, 2020 and 2019, respectively, and $2.9 million and $3.8 million during the nine months ended June 30, 2020 and 2019, respectively.
Contract Assets	Contract Assets The Company recognizes assets from the costs incurred to fulfill a contract including aircraft painting and reconfiguration and flight service personnel training costs. These costs are amortized based on the pattern of transfer of the services in relation to flight hours over the term of the contract. Contract assets are recorded as other assets in the condensed consolidated balance sheets. The Company's contract assets balances at June 30, 2020 and September 30, 2019 are $2.4 million and $3.9 million, respectively. Contract cost amortization was $0.3 million and $0.6 million for the three months ended June 30, 2020 and 2019, respectively, and $1.2 million and $1.8 million for the nine months ended June 30, 2020 and 2019, respectively.
Use of Estimates	Use of Estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates.
Maintenance Expense	Maintenance Expense The Company operates under a Federal Aviation Administration ("FAA") approved continuous inspection and maintenance program. The Company uses the direct expense method of accounting for its maintenance of regional jet engine overhauls, airframe, landing gear, and normal recurring maintenance wherein the Company recognizes the expense when the maintenance work is completed, or over the repair period, if materially different. Our maintenance policy is determined by fleet when major maintenance is incurred. For leased aircraft, the Company is subject to lease return provisions that require a minimum portion of the "life" of an overhaul be remaining on the engine at the lease return date. The Company estimates the cost of maintenance lease return obligations and accrues such costs over the remaining lease term when the expense is probable and can be reasonably estimated. Under the Company's aircraft operating lease agreements and FAA operating regulations, it is obligated to perform all required maintenance activities on its fleet, including component repairs, scheduled air frame checks and major engine restoration events. The Company estimates the timing of the next major maintenance event based on assumptions including estimated usage, FAA-mandated maintenance intervals and average removal times as recommended by the manufacturer. The timing and the cost of maintenance are based on estimates, which can be impacted by changes in utilization of its aircraft, changes in government regulations and suggested manufacturer maintenance intervals. Major maintenance events consist of overhauls to major components. Engine overhaul expense totaled $3.2 million and $11.4 million for the three months ended June 30, 2020, and 2019, respectively, of which $0.4 million and $1.9 million, respectively, was pass-through expense. Engine overhaul expense totaled $28.3 million and $20.8 million for the nine months ended June 30, 2020, and 2019, respectively, of which $3.0 million and $3.0 million, respectively, was pass-through expense. Airframe C-check expense totaled $2.9 million and $4.4 million for the three months ended June 30, 2020, and 2019, respectively, of which $0.8 million and $0.0 million, respectively, was pass-through expense. Airframe C-check expense totaled $20.6 million and $10.6 million for the nine months ended June 30, 2020, and 2019, respectively, of which $5.9 million and $0.0 million, respectively, was pass-through expense.

Contract Revenue and Pass- Through and Other (Tables)

9 Months Ended

Jun. 30, 2020

Revenue From Contract With Customer [Abstract]

Schedule of Deferred Revenue Remaining Performance Obligations

	Total Revenue
2020	$	—
2021		7,397
2022		8,603
Total	$	16,000

Intangible Assets (Tables)

9 Months Ended

Jun. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Information About Intangible Assets

Information about the intangible assets of the Company at June 30, 2020 and September 30, 2019, were as follows (in thousands):

	June 30,			September 30,
	2020			2019
Customer relationship	$	43,800		$	43,800
Accumulated amortization		(35,393	)		(34,268	)
	$	8,407		$	9,532

Balance Sheet Information (Tables)

9 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet

Certain significant amounts included in the Company's condensed consolidated balance sheet as of June 30, 2020 and September 30, 2019, consisted of the following (in thousands):

	June 30,			September 30,
	2020			2019
Expendable parts and supplies, net:
Expendable parts and supplies	$	26,368		$	25,336
Less: obsolescence and other		(3,950	)		(3,999	)
	$	22,418		$	21,337

Prepaid expenses and other current assets:
Prepaid aircraft rent	$	—		$	35,786
Deferred reimbursed costs		1,387			2,092
Other		5,756			3,045
	$	7,143		$	40,923
Property and equipment, net:
Aircraft and other flight equipment	$	1,597,916		$	1,582,199
Other equipment		5,323			5,122
Leasehold improvements		2,763			2,797
Vehicles		962			924
Building		699			699
Furniture and fixtures		303			302
Total property and equipment		1,607,966			1,592,043
Less: accumulated depreciation		(374,239	)		(318,458	)
	$	1,233,727		$	1,273,585

Other accrued expenses:
Accrued property taxes	$	9,035		$	9,186
Accrued interest		5,941			4,497
Accrued vacation		5,767			6,128
Deferred revenue-current portion		3,760			—
Other		13,160			9,077
	$	37,663		$	28,888

Fair Value Measurements (Tables)

9 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Maturities

The carrying value and estimated fair value of the Company's long-term debt, including current maturities, were as follows (in millions):

	Jun 30, 2020				September 30, 2019
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
Long-term debt and financing leases, including current maturities(1)	$	777.8	$	857.2	$	858.1	$	882.7

(1)

Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Long-Term Debt, Financing Leases and Other Borrowings (Tables)

9 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt as of June 30, 2020 and September 30, 2019, consisted of the following (in thousands):

	June 30,			September 30,
	2020			2019
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2022⁽¹⁾⁽²⁾	$	41,472		$	49,795
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2024⁽³⁾		55,674			60,761
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2027⁽⁴⁾		105,786			110,912
Notes payable to secured parties, collateralized by the underlying
aircraft, due 2028⁽⁵⁾		181,776			191,168
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2028⁽⁶⁾		141,871			152,945
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2022⁽⁷⁾		53,647			71,998
Senior and subordinated notes payable to secured parties, collateralized
by the underlying aircraft, due 2022⁽⁸⁾		34,607			47,309
Notes payable to financial institution, collateralized by the underlying
equipment, due 2020⁽⁹⁾		415			1,659
Notes payable to financial institution due 2020⁽¹⁰⁾		1,523			2,329
Notes payable to financial institution, collateralized by the underlying
equipment, due 2022⁽¹¹⁾		4,182			6,962
Other obligations due to financial institution, collateralized by the underlying
equipment, due 2023⁽¹²⁾		7,196			8,530
Notes payable to financial institution, collateralized by the underlying
equipment, due 2024⁽¹³⁾		67,631			80,153
Notes payable to financial institution, collateralized by the underlying
aircraft, due 2023⁽¹⁴⁾		52,500			65,625
Notes payable to financial institution, collateralized by the underlying
equipment, due 2023⁽¹⁵⁾		6,500			8,000
Working capital draw loan, used to cover operational needs ⁽¹⁶⁾		23,000			—
Gross long-term debt, including current maturities		777,780			858,145
Less unamortized debt issuance costs		(14,007	)		(14,822	)
Net long-term debt, including current maturities		763,773			843,323
Less current portion		(176,896	)		(165,900	)
Net long-term debt	$	586,877		$	677,423

⁽¹⁾	In fiscal 2007, the Company financed three CRJ-900 and three CRJ-700 aircraft for $120.3 million. The debt bears interest at the monthly LIBOR plus 2.25% (2.41% at June 30, 2020) and requires monthly principal and interest payments.

⁽²⁾

⁽³⁾	In fiscal 2014, the Company financed eight CRJ-900 aircraft with $114.5 million in debt. The debt bears interest at 5.00% and requires monthly principal and interest payments.

⁽⁴⁾

⁽⁵⁾	In fiscal 2016, the Company financed ten E-175 aircraft with $246.0 million in debt under an EETC financing arrangement (see discussion below). The debt bears interest ranging from 4.75% to 6.25% and requires semi-annual principal and interest payments.

⁽⁶⁾

⁽⁷⁾

⁽⁸⁾

⁽⁹⁾	In fiscal 2015, the Company financed certain flight equipment with $8.3 million in debt. The debt bears interest at 5.163% and requires monthly principal and interest payments.

⁽¹⁰⁾	In fiscal 2015 and 2016, the Company financed certain flight equipment maintenance costs with $10.2 million in debt. The debt bears interest at the three-month LIBOR plus 3.07% (3.37% at June 30, 2020) and requires quarterly principal and interest payments.

⁽¹¹⁾

¹²⁾	In February 2018, the Company leased two spare engines. The leases were determined to be capital as the leases contain a bargain purchase option at the end of the term. Imputed interest is 9.128% and the leases requires monthly payments.

⁽¹³⁾	In January 2019, the Company financed certain flight equipment with $91.2 million in debt. The debt bears interest at the monthly LIBOR plus 3.10% (3.26% at June 30, 2020) and requires monthly principal and interest payments.

⁽¹⁴⁾

⁽¹⁵⁾

⁽¹⁶⁾

Schedule of Principal Maturities of Long-term Debt

Principal maturities of long-term debt as of June 30, 2020, and for each of the next five years are as follows (in thousands):

Periods Ending June 30,	Total Principal
Remainder of 2020	$	178,459
2021		162,494
2022		133,663
2023		79,268
2024		55,677
Thereafter		168,219
	$	777,780

Earnings Per Share and Equity (Tables)

9 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Calculations of Net Income Per Common Share

Calculations of net income per common share attributable to Mesa Air Group were as follows (in thousands, except per share data):

	Three Months Ended June 30,				Nine Months Ended June 30,
	2020		2019		2020		2019
Net income attributable to Mesa Air Group	$	3,419	$	3,007	$	16,089	$	35,337
Basic weighted average common shares outstanding		35,299		34,835		35,154		34,683
Add: Incremental shares for: (1)
Dilutive effect of restricted stock		—		277		94		368
Diluted weighted average common shares outstanding		35,299		35,112		35,248		35,051
Net income per common share attributable to Mesa Air Group:
Basic	$	0.10	$	0.09	$	0.46	$	1.02
Diluted	$	0.10	$	0.09	$	0.46	$	1.01

Share-Based Compensation and Stock Repurchases (Tables)

9 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Restricted Share Activity

The restricted share activity for the nine months ended June 30, 2020 were summarized as follows:

				Weighted-
				Average
	Number			Grant Date
	of Shares			Fair Value
Restricted shares unvested at September 30, 2019		847,974		$	9.56
Granted		660,297			4.07
Vested		(468,697	)		9.69
Forfeited		(6,000	)		7.03
Restricted shares unvested at June 30, 2020		1,033,574		$	6.01

Leases and Commitments (Tables)

9 Months Ended

Jun. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Schedule of Lease Related Terms and Discount Rates

The table below presents lease related terms and discount rates as of June 30, 2020:

As of June 30, 2020

Weighted average remaining lease term Operating

leases

3.8 years

Weighted average discount rate Operating leases

4.2

Schedule of Operating Lease Cost

	Three Months Ended June 30,
	2020		2019		$ Change			% Change
Operating lease cost	$	15,634	$	18,094	$	(2,460	)		(13.6	)%


	Nine Months Ended June 30,
	2020		2019		$ Change			% Change
Operating lease cost	$	51,000	$	55,897	$	(4,897	)		(8.8	)%

Schedule of Future Minimum Rental Payments under Operating Leases of Initial or Remaining Non-cancelable Lease Terms

Periods Ending June 30,	Total Maturities
2020	$	9,390
2021		47,377
2022		33,216
2023		15,947
2024		14,682
Thereafter		1,654
Less: Interest	$	(7,892	)
Amounts recorded in the Consolidated Balance Sheet	$	114,374

Schedule of Future Minimum Lease Obligations under Non-cancelable Operating Leases

The following represents future minimum lease obligations under non-cancelable operating leases as of September 30, 2019 (in thousands):

Periods Ending September 30,	Total Payments
2020	$	47,814
2021		46,007
2022		31,090
2023		13,726
2024		13,185
Thereafter		1,368
Total	$	153,190

Supplemental Disclosure (Tables)

9 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Elements [Abstract]

Reconciliation of Captions in Condensed Consolidated Balance Sheets to Condensed Consolidated Statements of Cash Flows

The following is a reconciliation of the captions in the Condensed Consolidated Balance Sheets to the Condensed Consolidated Statements of Cash Flows (in thousands):

	June 30,		September 30,
	2020		2019
Condensed Consolidated Balance Sheets
Cash and cash equivalents	$	64,934	$	68,855
Restricted cash		3,444		3,646
Cash, cash equivalents, and restricted cash in Condensed Consolidated Statement of Cash Flows	$	68,378	$	72,501

Organization and Operations - Additional Information (Detail) $ in Thousands							1 Months Ended		3 Months Ended	9 Months Ended
	Jun. 15, 2020 Air-craft	Apr. 03, 2020 Air-craft	Jan. 02, 2020 Air-craft	Nov. 26, 2019 Air-craft	Nov. 25, 2019 Air-craft	Jan. 31, 2019 Air-craft	Apr. 30, 2020 USD ($) Installment	Jul. 31, 2019 Air-craft	Jun. 30, 2020 USD ($) Daily_Departure State	Jun. 30, 2020 USD ($) Daily_Departure State Air-craft City Employee	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Apr. 02, 2019 Air-craft
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of states in which entity operates \| State									29	29
Number of aircrafts operated										145
Number of cities in which entity operates \| City										66
Number of daily departures \| Daily_Departure									175	175
Number of employees \| Employee										3,400
Cash and cash equivalents \| $									$ 64,934	$ 64,934		$ 68,855
Reducing planned heavy engine and airframe maintenance events \| $										16,800
Drew amount from undrawn revolving credit facility \| $										$ 23,000	$ 163,658
CARES act grant amount \| $							$ 92,500
CARES act, grants received \| $							46,300
CARES act, remaining grants yet to receive \| $							$ 46,200
Number of installments to receive remaining grants \| Installment							3
CARES act, utilized offset payroll expenses \| $									43,000
CARES act, deferred offset future payroll cost \| $									$ 3,300
CARES Act of 2020 loan amount allocated under loan program \| $							$ 277,000
Maximum number of aircraft to permanently withdraw in the event company fails to meet new/ revise performance metrics						6
Number of aircraft converted to be utilized as operational spares													2
Number of aircraft permanently withdraw due to failure to meet new/revised performance metrics	2							2
American capacity purchase agreement termination notice period										15 days
Number of additional aircraft permanently withdrawn due to company's failure to meet certain performance metrics					2
Number of deferred aircraft elected to remove			1
Maximum number of aircraft to withdraw in the event company fails to meet new/ revise performance metrics										14
Number of aircraft removed due to failure to meet new/revised performance metrics			3
Number of aircraft that would be withdrawn at any time due to failure to meet new/revised performance metrics		3
Notice period for termination of agreement										Our United Capacity Purchase Agreement permits United, subject to certain conditions, including the payment of certain costs tied to aircraft type, to terminate the agreement in its discretion, or remove aircraft from service, by giving us notice of 90 days or more.
United capacity purchase agreement termination notice period										30 days
Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Capacity purchase agreement, expiration year										2021
Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Capacity purchase agreement, expiration year										2025
CRJ-900 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated										54
CRJ-900 Aircraft [Member] \| Aircraft Lease Expire In 2021 [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operated aircrafts expired or set to expire										31
Lease expiration year										2021
CRJ-900 Aircraft [Member] \| Aircraft Lease Expire In 2021 [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operated aircrafts expired or set to expire										16
Lease expiration year										2022
CRJ-900 Aircraft [Member] \| Aircraft Lease Expire In 2025 [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operated aircrafts expired or set to expire										7
Lease expiration year										2025
CRJ-700 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated										20
CRJ-700 Aircraft [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Aircraft lease term				7 years
E-175 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated				18						60
Lease expiration year				2028
E-175 Aircraft [Member] \| Mesa [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated										18
E-175 Aircraft [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated				42						42
Aircraft lease extension period				5 years
E-175 Aircraft [Member] \| Minimum [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year				2024
E-175 Aircraft [Member] \| Maximum [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year				2028
E175LL Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of additional aircrafts				20
Number of years in operation				12 years
Air drafts delivery month and year description.										Deliveries of the new E175LL aircraft were scheduled to begin in May 2020 and be completed by December 31, 2020.
Termination of aircraft operation, description										Commencing five (5) years after the actual in-service date, United has the right to remove the E175LL aircraft from service by giving us notice of 90 days or more, subject to certain conditions, including the payment of certain wind-down expenses plus, if removed prior to the ten (10) year anniversary of the in-service date, certain accelerated margin payments.
Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Drew amount from undrawn revolving credit facility \| $										$ 23,000

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Summary Of Significant Accounting Policies [Line Items]
Current and non-current deferred credit balances	$ 9.4		$ 9.4		$ 12.1
Recognized deferred credits to revenue	0.9	$ 1.3	2.9	$ 3.8
Contract assets balances	2.4		2.4		$ 3.9
Contract cost amortization	0.3	0.6	1.2	1.8
Engine overhaul expense	3.2	11.4	28.3	20.8
Engine overhaul pass-through expense	0.4	1.9	3.0	3.0
Airframe check expense	2.9	4.4	20.6	10.6
Airframe check pass-through expense	$ 0.8	$ 0.0	$ 5.9	$ 0.0
Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage leased			12.00%

Contract Revenue and Pass- Through and Other - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 16,000		$ 16,000
Deferred revenue, current	3,760		3,760
Deferred revenue, noncurrent	12,240		12,240
Contract Revenue [Member]
Disaggregation Of Revenue [Line Items]
Lease revenue	52,000	$ 54,500	157,700	$ 164,500
Other Accrued Expenses [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue, current	$ 3,800		$ 3,800

Contract Revenue and Pass- Through and Other - Schedule of Deferred Revenue Remaining Performance Obligations (Detail) $ in Thousands	Jun. 30, 2020 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 16,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-07-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-07-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 7,397
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-07-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 8,603
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year

Contract Revenue and Pass- Through and Other - Schedule of Deferred Revenue Remaining Performance Obligations (Detail 1) $ in Thousands	Jun. 30, 2020 USD ($)
Revenue Performance Obligation Satisfied Over Time [Abstract]
Total Revenue	$ 16,000

Recent Accounting Pronouncements - Additional Information (Detail) - USD ($)	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Oct. 01, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings	$ 445,494,000	$ 441,352,000	$ 438,191,000		$ 425,868,000	$ 412,734,000	$ 409,285,000	$ 395,159,000	$ 374,467,000
Accounting Standards Update 2016-02 [Member] \| Cumulative Effect Period Of Adoption Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings				$ 0

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References + Details

Concentrations - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Concentration Risk [Line Items]
Allowance for doubtful accounts	$ 5.4		$ 5.4		$ 1.0
Sales Revenue, Net [Member] \| American Airlines Inc. [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	60.00%	53.00%	53.00%	54.00%
Sales Revenue, Net [Member] \| United [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	40.00%	47.00%	47.00%	46.00%

Intangible Assets - Information About Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Intangible Assets Net Excluding Goodwill [Abstract]
Customer relationship	$ 43,800	$ 43,800
Accumulated amortization	(35,393)	(34,268)
Total	$ 8,407	$ 9,532

Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Intangible Assets Net Excluding Goodwill [Abstract]
Amortization expense recognized	$ 0.4	$ 0.5	$ 1.1	$ 1.4
Amortization expense for remainder of 2020	0.4		0.4
Amortization expense for 2021	1.2		1.2
Amortization expense for 2022	1.0		1.0
Amortization expense for 2023	0.9		0.9
Amortization expense for 2024	$ 0.8		$ 0.8

Balance Sheet Information - Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Expendable parts and supplies, net:
Expendable parts and supplies	$ 26,368	$ 25,336
Less: obsolescence and other	(3,950)	(3,999)
Expendable parts and supplies, net	22,418	21,337
Prepaid expenses and other current assets:
Prepaid aircraft rent		35,786
Deferred reimbursed costs	1,387	2,092
Other	5,756	3,045
Prepaid expenses and other current assets	7,143	40,923
Property and equipment, net:
Property and equipment-gross	1,607,966	1,592,043
Less: accumulated depreciation	(374,239)	(318,458)
Property and equipment-net	1,233,727	1,273,585
Other accrued expenses:
Accrued property taxes	9,035	9,186
Accrued interest	5,941	4,497
Accrued vacation	5,767	6,128
Deferred revenue-current portion	3,760
Other	13,160	9,077
Other accrued expenses	37,663	28,888
Aircraft and Other Flight Equipment [Member]
Property and equipment, net:
Property and equipment-gross	1,597,916	1,582,199
Other Machinery and Equipment [Member]
Property and equipment, net:
Property and equipment-gross	5,323	5,122
Leasehold Improvements [Member]
Property and equipment, net:
Property and equipment-gross	2,763	2,797
Vehicles [Member]
Property and equipment, net:
Property and equipment-gross	962	924
Building [Member]
Property and equipment, net:
Property and equipment-gross	699	699
Furniture and Fixtures [Member]
Property and equipment, net:
Property and equipment-gross	$ 303	$ 302

Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 20,200	$ 19,300	$ 60,500	$ 56,200
Amortization of unfavorable lease liability		$ 1,400		$ 4,525

Fair Value Measurements - Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Maturities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Long-term debt and finance leases, including current maturities, carrying value	$ 777,780	$ 858,145
Long-term debt and finance leases, including current maturities, fair value	$ 857,200	$ 882,700

Long-Term Debt, Financing Leases and Other Borrowings - Schedule of Long-term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 777,780	$ 858,145
Less unamortized debt issuance costs	(14,007)	(14,822)
Net long-term debt, including current maturities	763,773	843,323
Less current portion	(176,896)	(165,900)
Net long-term debt	586,877	677,423
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	41,472	49,795
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	55,674	60,761
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	105,786	110,912
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	181,776	191,168
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	141,871	152,945
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	53,647	71,998
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	34,607	47,309
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	415	1,659
Notes Payable to Financial Institution Due 2020 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	1,523	2,329
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	4,182	6,962
Other Obligations Due to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	7,196	8,530
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	67,631	80,153
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	52,500	65,625
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	6,500	$ 8,000
Working Capital Draw Loan, Used to Cover Operational Needs [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 23,000

Long-Term Debt, Financing Leases and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail) $ in Thousands				1 Months Ended					3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 27, 2019 USD ($)	Sep. 25, 2019 USD ($)	Jun. 14, 2019 USD ($)	Jun. 30, 2019 USD ($) Airfleet	Jan. 31, 2019 USD ($)	Jun. 30, 2018 USD ($) Air-craft	Feb. 28, 2018 Engine	Dec. 31, 2017 USD ($) Air-craft	Mar. 31, 2020 USD ($)	Dec. 31, 2019	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) Airfleet	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) Air-craft	Sep. 30, 2015 USD ($) Air-craft	Sep. 30, 2007 USD ($) Airfleet	Sep. 30, 2014 USD ($) Airfleet
Debt Instrument [Line Items]
Proceeds from long-term debt											$ 23,000	$ 163,658
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from long-term debt											$ 23,000
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2022		2022
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet																		3
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-700 [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Airfleet																		3
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Three C- R- J-900 and Three C- R- J-700 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																		$ 120,300
Long term debt interest rate percentage											2.41%
Long term debt interest rate description											monthly LIBOR plus 2.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Three C- R- J-900 and Three C- R- J-700 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate																		2.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																			$ 88,400
Long term debt interest rate description											monthly LIBOR plus a spread ranging from 1.95% to 7.25%
Number of aircraft financed \| Airfleet																			10
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											2.11%								1.95%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Ten C- R- J-900 Aircraft [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											7.41%								7.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| Four C- R- J-900 Aircraft [Member]
Debt Instrument [Line Items]
Repayments of long term debt														$ 40,000
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2024		2024
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2024 [Member] \| Eight C- R- J-900 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																			$ 114,500
Number of aircraft financed \| Airfleet																			8
Long term debt interest rate percentage																			5.00%
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2027		2027
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																	$ 170,200
Number of aircraft financed \| Air-craft																	7
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2028		2028
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																$ 246,000
Number of aircraft financed \| Air-craft																10
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											4.75%
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Ten E-175 Aircraft [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											6.25%
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2028		2028
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] \| Eight E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Number of aircraft refinanced \| Air-craft																8
Debt instrument, face amount																$ 195,300
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2022		2022
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2022		2022
Number of aircraft refinanced \| Air-craft						6		9
Debt instrument, face amount						$ 27,500		$ 74,900
Number of aircraft financed \| Air-craft						9
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2022 [Member] \| CRJ-900 [Member] \| Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 69,600
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2020 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2020		2020
Debt instrument, face amount																	$ 8,300
Long term debt interest rate percentage																	5.163%
Notes Payable to Financial Institution Due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2020		2020
Notes Payable to Financial Institution Due 2020 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																$ 10,200	$ 10,200
Long term debt interest rate percentage											3.37%
Long term debt interest rate description											three-month LIBOR plus 3.07%
Notes Payable to Financial Institution Due 2020 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage																3.07%	3.07%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2022		2022
Debt instrument, face amount													$ 26,100	$ 26,100	$ 26,100	$ 26,100
Long term debt interest rate description											Three-month LIBOR plus a spread ranging from 2.93% to 3.21%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											3.23%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											3.51%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate													2.93%	2.93%	2.93%	2.93%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2022 [Member] \| Flight Equipment Maintenance [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate													3.21%	3.21%	3.21%	3.21%
Other Obligations Due to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2023		2023
Imputed interest							9.128%
Number of spare engines leased \| Engine							2
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2024		2024
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 91,200
Long term debt interest rate percentage											3.26%
Long term debt interest rate description											monthly LIBOR plus 3.10%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] \| Flight Equipment [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate					3.10%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2023		2023
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| CRJ-700 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 70,000	$ 70,000								$ 70,000
Long term debt interest rate percentage											5.16%
Long term debt interest rate description			LIBOR plus 5.0%								monthly LIBOR plus 5.00%
Number of aircraft financed \| Airfleet				10								10
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| CRJ-700 Aircraft [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate				5.00%						5.00%	5.00%		5.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year											2023		2023
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member] \| Flight Equipment [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 8,000
Long term debt interest rate percentage											5.16%
Long term debt interest rate description											monthly LIBOR plus 5.00%
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member] \| Flight Equipment [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate	5.00%									5.00%			5.25%
Senior Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																	$ 151,000
Long term debt interest rate percentage											2.87%
Long term debt interest rate description											monthly LIBOR plus 2.71%
Senior Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate																	2.71%
Subordinated Notes Due Two Thousand Twenty Seven [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Imputed interest																	6.25%
Debt discount																	$ 8,100
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member]
Debt Instrument [Line Items]
Long term debt interest rate description											Three-month LIBOR plus a spread ranging from 2.20% to 2.32%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, face amount																$ 172,000
Long term debt interest rate percentage											2.50%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											2.62%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate																2.20%
Senior Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate																2.32%
Subordinated Notes Due 2008 [Member] \| Eight E-175 Aircraft [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											4.50%
Senior Notes Due 2020 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 65,800
Long term debt interest rate percentage											3.80%
Long term debt basis spread on variable rate						3.50%
Senior Notes Due 2020 [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate description											three-month LIBOR plus 3.50%
Subordinated Notes Due 2020 [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 29,800
Long term debt interest rate percentage											7.80%
Long term debt basis spread on variable rate						7.50%
Subordinated Notes Due 2020 [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate description											three month LIBOR plus 7.50%
Senior Notes due Two Thousand Twenty Two [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								$ 46,900
Long term debt interest rate percentage											3.80%
Long term debt interest rate description											three-month LIBOR plus 3.50%
Senior Notes due Two Thousand Twenty Two [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate								3.50%
Subordinated Notes DueTwoThousandTwentyTwo [Member] \| CRJ-900 [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage											4.80%
Long term debt interest rate description											three-month LIBOR plus 4.50%
Subordinated Notes DueTwoThousandTwentyTwo [Member] \| CRJ-900 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt interest rate percentage								4.50%
Working Capital Draw Loan [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 35,000
Long term debt interest rate description											one-month LIBOR plus 3.75%
Term loan, term		3 years
Debt instrument, expiration year and month		2022-09
Proceeds from long-term debt									$ 23,000
Working Capital Draw Loan [Member] \| LIBOR [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt basis spread on variable rate		3.75%

Long-Term Debt, Financing Leases and Other Borrowings - Schedule of Principal Maturities of Long-term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Long Term Debt By Maturity [Abstract]
Remainder of 2020	$ 178,459
2021	162,494
2022	133,663
2023	79,268
2024	55,677
Thereafter	168,219
Long-term debt	$ 777,780	$ 858,145

Long-Term Debt, Financing Leases and Other Borrowings - Additional Information (Detail) $ in Thousands					1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 27, 2019 USD ($)	Sep. 25, 2019 USD ($)	Jun. 14, 2019 USD ($) Air-craft	Jan. 28, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Apr. 09, 2020 USD ($)
Debt Instrument [Line Items]
Property and equipment, net									$ 1,233,727		$ 1,273,585
Long-Term Debt									763,773		$ 843,323
Loss on extinguishment of debt										$ 3,616
Payment for debt extinguishment prepayment penalties										1,672
Non-cash lease termination expense								$ 9,540		9,540
Proceeds from long-term debt									23,000	163,658
Lease payment amount									114,374
Export Development Canada [Member]
Debt Instrument [Line Items]
Debt instrument, face amount												$ 28,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from long-term debt									23,000
Equipment Notes [Member]
Debt Instrument [Line Items]
Long-Term Debt									$ 181,800
Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 91,200
Long term debt interest rate description									LIBOR plus 3.10%
Term loan, term				5 years
Write-off of financing cost				$ 1,900
Payment for debt extinguishment prepayment penalties				1,700
Term Loan [Member] \| Spare Engine Facility [Member]
Debt Instrument [Line Items]
Long term debt interest rate description									LIBOR plus 7.25%
Loss on extinguishment of debt				$ 3,600
Term Loan [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate				3.10%
Term Loan [Member] \| LIBOR [Member] \| Spare Engine Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate				7.25%
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| CRJ-700 Aircraft [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 70,000		$ 70,000			$ 70,000		$ 70,000
Long term debt interest rate description			LIBOR plus 5.0%						monthly LIBOR plus 5.00%
Number of aircraft purchased \| Air-craft			10
Payment for aircraft purchased			$ 70,000
Non-cash lease termination expense			$ 9,500
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] \| LIBOR [Member] \| CRJ-700 Aircraft [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate					5.00%		5.00%		5.00%		5.25%
Working Capital Draw Loan [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 35,000
Long term debt interest rate description									one-month LIBOR plus 3.75%
Term loan, term		3 years
Debt instrument, expiration year and month		2022-09
Proceeds from long-term debt						$ 23,000
Working Capital Draw Loan [Member] \| LIBOR [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate		3.75%
Aircraft and Equipment [Member] \| Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment, net									$ 1,114,000
Flight Equipment [Member] \| Notes Payable to Financial Institution Due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 8,000
Long term debt interest rate description	Libor plus 5.0%.
Flight Equipment [Member] \| Notes Payable to Financial Institution Due 2023 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate									5.00%
RASPRO Aircraft Lease [Member]
Debt Instrument [Line Items]
Lease payment amount									$ 4,000

Earnings Per Share and Equity - Calculations of Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share And Equity [Abstract]
Net income	$ 3,419	$ 1,885	$ 10,785	$ 3,007	$ 13,249	$ 19,081	$ 16,089	$ 35,337
Basic weighted average common shares outstanding	35,299			34,835			35,154	34,683
Add: Incremental shares for:
Dilutive effect of restricted stock				277			94	368
Diluted weighted average common shares outstanding	35,299			35,112			35,248	35,051
Net income per common share attributable to Mesa Air Group:
Basic	$ 0.10			$ 0.09			$ 0.46	$ 1.02
Diluted	$ 0.10			$ 0.09			$ 0.46	$ 1.01

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Earnings Per Share and Equity - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restricted Stock [Member]
Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted loss per share	0	0	0	0
Number of Warrants [Member]
Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted loss per share	0	0	0	0

Common Stock - Additional Information (Detail) $ / shares in Units, $ in Millions					9 Months Ended
	Apr. 09, 2019	Sep. 11, 2018 $ / shares shares	Aug. 14, 2018 $ / shares shares	Aug. 08, 2018 shares	Jun. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 $ / shares shares
Class of Warrant or Right [Line Items]
Warrants term					5 years
Warrants of common stock exercise price \| $ / shares					$ 0.004
Maximum percentage of stock pertaining to restrictions					24.90%
Extended term of outstanding warrants expiration period					5 years
Warrants of common stock expiration date					Sep. 30, 2023
Common stock, stock split					effected a 2.5-for-1 stock split
Stock split ratio				2.5
Common stock, shares authorized				125,000,000	125,000,000	125,000,000
Preferred stock, shares authorized				5,000,000	5,000,000	5,000,000
Stock issued during period, shares, new issues		1,344,500
Common stock, no par value \| $ / shares					$ 0	$ 0
Common stock, warrants issued					0	3,600,953
2018 Equity Incentive Plan [Member]
Class of Warrant or Right [Line Items]
Common stock, stock split					2.5-for-1 stock split effected
Stock split ratio	2.5
Increase in number of shares authorized for issuance				1,000,000
IPO [Member]
Class of Warrant or Right [Line Items]
Stock issued during period, shares, new issues			9,630,000
Common stock, no par value \| $ / shares
Shares issued, price per share \| $ / shares			$ 12.00
Gross proceeds of initial public offering \| $					$ 124.2
Net proceeds from initial public offering \| $					111.7
Underwriting discounts and commissions \| $					8.7
Offering costs \| $					$ 3.6
Underwriter Options [Member]
Class of Warrant or Right [Line Items]
Common stock, warrants issued			1,444,500
Purchased Directly From Company [Member]
Class of Warrant or Right [Line Items]
Stock issued during period, shares, new issues		723,985
Purchased Directly From Selling Shareholders [Member]
Class of Warrant or Right [Line Items]
Stock issued during period, shares, new issues		620,515
Firm Shares and Option Shares [Member]
Class of Warrant or Right [Line Items]
Shares issued, price per share \| $ / shares		$ 12.00

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Income Taxes [Line Items]
Effective tax rate (ETR) from continuing operations	30.70%	22.20%	28.30%	23.60%
State net operating loss carryforwards					$ 2.7
Domestic Tax Authority [Member] \| 2027-2037 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					478.3
State and Local Jurisdiction [Member] \| 2020-2039 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					$ 228.3
Minimum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2027
Minimum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2020
Maximum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2037
Maximum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2039

Share-Based Compensation and Stock Repurchases - Schedule of Restricted Share Activity (Detail) - Restricted Stock [Member]	9 Months Ended
	Jun. 30, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance \| shares	847,974
Number of Shares, Granted \| shares	660,297
Number of Shares, Vested \| shares	(468,697)
Number of Shares, Forfeited \| shares	(6,000)
Number of Shares, Unvested, Ending Balance \| shares	1,033,574
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance \| $ / shares	$ 9.56
Weighted-Average Grant Date Fair Value, Granted \| $ / shares	4.07
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	9.69
Weighted-Average Grant Date Fair Value, Forfeited \| $ / shares	7.03
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance \| $ / shares	$ 6.01

Share-Based Compensation and Stock Repurchases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended					9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 5,000					$ 5,000
Unrecognized compensation cost, period for recognition						2 years 4 months 24 days
Share-based compensation expense	1,000			$ 1,500		$ 3,500	$ 4,300
Repurchased shares, value	$ 297	$ 160	$ 41	$ 1,065	$ 449
Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						1 year
Restricted Stock Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						3 years
Restricted Stock Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						5 years
Restricted Stock Award \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						3 years
Restricted Stock Award \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						5 years
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchased shares, shares						112,587
Repurchased shares, value						$ 500

Employee Stock Purchase Plan - Additional Information (Detail) - 2019 ESPP [Member]	9 Months Ended
	Jun. 30, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares, discount rate	10.00%
Number of ordinary shares issued	43,934
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual	1.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual	15.00%
Number of ordinary shares issued	500,000

Leases and Commitments - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020 USD ($) Air-craft	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Air-craft Engine	Jun. 30, 2019 USD ($)	Oct. 01, 2019 USD ($)
Operating Leased Assets [Line Items]
Operating lease, right-of-use assets	$ 131,480		$ 131,480
Number of leased aircraft \| Air-craft	18		18
Aggregate rental expense under all operating aircraft, equipment and facility leases	$ 15,600	$ 18,100	$ 51,000	$ 55,900
Operating lease current liabilities	43,219		43,219
Operating lease noncurrent liabilities	71,068		71,068
Operating lease payments in operating cash flows			34,919
CF34-8C5 Engine [Member] \| Letter Agreement [Member]
Operating Leased Assets [Line Items]
Purchase commitment amount	$ 108,000		$ 108,000
CF34-8C5 Engine [Member] \| Letter Agreement No. 13-1 [Member]
Operating Leased Assets [Line Items]
Number of new spare engines to be acquired \| Engine			20
New spare engines delivery month and year description			Under Letter Agreement No. 13-1, the Company has agreed to purchase and take delivery of 20 new spare CF34-8C5 engines. Delivery of the new spare engines will now commence in April 2021, with the final spare engine being delivered in December 2021.
New Spare engines payments commencing month and year description			The payment terms for the new spare engines were also amended, with payments to now be made in four (4) separate tranches commencing in October and December 2020 and February and March 2021.
Accounting Standards Update 2016-02 [Member]
Operating Leased Assets [Line Items]
Operating lease, right-of-use assets					$ 154,600
Operating lease, liability					141,900
Accounting Standards Update 2016-02 [Member] \| Prepaid Aircraft Rent [Member]
Operating Leased Assets [Line Items]
Operating lease, right-of-use assets					35,800
Accounting Standards Update 2016-02 [Member] \| Deferred Rent Credits [Member]
Operating Leased Assets [Line Items]
Operating lease, right-of-use assets					21,300
Accounting Standards Update 2016-02 [Member] \| Accrued Aircraft Rents [Member]
Operating Leased Assets [Line Items]
Operating lease, right-of-use assets					$ 1,800

Leases and Commitments - Schedule of Lease Related Terms and Discount Rates (Detail)	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Weighted average remaining lease term Operating leases	3 years 9 months 18 days
Weighted average discount rate Operating leases	4.20%

Leases and Commitments - Schedule of Operating Lease Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 15,634	$ 18,094	$ 51,000	$ 55,897
Change in operating lease cost	$ (2,460)		$ (4,897)
Percentage of change in operating lease cost	(13.60%)		(8.80%)

Leases and Commitments - Schedule of Future Minimum Rental Payments under Operating Leases of Initial or Remaining Non-cancelable Lease Terms (Detail) $ in Thousands	Jun. 30, 2020 USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2020	$ 9,390
2021	47,377
2022	33,216
2023	15,947
2024	14,682
Thereafter	1,654
Less: Interest	(7,892)
Amounts recorded in the Consolidated Balance Sheet	$ 114,374

Leases and Commitments - Schedule of Future Minimum Lease Obligations under Non-cancelable Operating Leases (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2020	$ 47,814
2021	46,007
2022	31,090
2023	13,726
2024	13,185
Thereafter	1,368
Total	$ 153,190

Supplemental Disclosure - Reconciliation of Captions in Condensed Consolidated Balance Sheets to Condensed Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 64,934	$ 68,855
Restricted cash	3,444	3,646
Cash, cash equivalents, and restricted cash in Condensed Consolidated Statement of Cash Flows	$ 68,378	$ 72,501	$ 83,556	$ 107,134