Employee Stock Purchase Plan	12 Months Ended
Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Employee Stock Purchase Plan	15. 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 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 September 30, 2023, eligible employees purchased and the Company issued an aggregate of 444,590 Mesa Air Group, Inc. ordinary shares under the 2019 ESPP, 140,453 of which were purchased and issued during the current fiscal year.

The entire disclosure for shareholders' equity and share-based payment arrangement. Includes, but is not limited to, disclosure of policy and terms of share-based payment arrangement, deferred compensation arrangement, and employee stock purchase plan (ESPP).

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-Topic 505
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 718
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//718/tableOfContent

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