Amended and restated bylaws descriptions.

No definition available.

Name:	mesa_AmendedAndRestatedBylawsDescriptions
Namespace Prefix:	mesa_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Common stock issued equivalent percentage of issued and outstanding capital stock.

+ References

No definition available.

+ Details

Name:	mesa_CommonStockIssuedEquivalentPercentageOfIssuedAndOutstandingCapitalStock
Namespace Prefix:	mesa_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face amount per share of no-par value common stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockNoParValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

+ Details

Name:	us-gaap_CommonStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=mesa_UnitedCapacityPurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=mesa_UnitedAirlinesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events - Additional Information (Detail) - $ / shares		3 Months Ended
	Jan. 13, 2023	Dec. 31, 2022	Sep. 30, 2022
Subsequent Event [Line Items]
Common stock, shares issued		36,378,550	36,376,897
Common stock, no par value		$ 0	$ 0
United Capacity Purchase Agreement [Member]
Subsequent Event [Line Items]
Amended and restated bylaws descriptions		On January 13, 2023, the Company’s Board of Directors approved a resolution to amend the Company’s Amended and Restated Bylaws (the “Bylaws”) in connection with the Company’s entry into the Amended and Restated United CPA, see Note 1, which provides United with the right to designate one (1) representative to be a member of the Board, provided that United holds at least five percent (5%) of the issued and outstanding shares of capital stock of the Company, and provided that such United Designee shall be subject to the reasonable approval of the Board. Until the earlier of January 1, 2026, or the Company’s entry into a definitive binding agreement for the performance of regional airline services with a major air carrier other than United, the Board shall not take, or make any recommendation to the stockholders of the Company
Subsequent Event [Member] \| United Capacity Purchase Agreement [Member] \| United [Member]
Subsequent Event [Line Items]
Common stock, shares issued	4,042,061
Common stock, no par value	$ 0
Common stock issued equivalent percentage of issued and outstanding capital stock	10.00%