Document and Entity Information
3 Months Ended
Dec. 31, 2019
Cover [Abstract]  
Document Type 10-Q
Amendment Flag false
Document Period End Date Dec. 31, 2019
Document Fiscal Year Focus 2020
Document Fiscal Period Focus Q1
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 33,039,126