Additional collateral coverage ratio.

No definition available.

Name:	mesa_AdditionalCollateralCoverageRatio1
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Balance Type:	na
Period Type:	duration

- Definition

Calculated collateral coverage ratio.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Covenant capping restricted payments.

+ References

No definition available.

+ Details

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Namespace Prefix:	mesa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt instrument additional amount borrowed.

+ References

No definition available.

+ Details

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Namespace Prefix:	mesa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument amount borrowed.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Line of credit, revolving commitments.

+ References

No definition available.

+ Details

Name:	mesa_LineOfCreditRevolvingCommitments
Namespace Prefix:	mesa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Minimum collateral coverage ratio 1.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of all in rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	mesa_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Remaining balance

+ References

No definition available.

+ Details

Name:	mesa_RemainingBalance
Namespace Prefix:	mesa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Rental coverage ratio.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
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-Name Accounting Standards Codification
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-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

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Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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-Paragraph 1
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+ Details

Name:	us-gaap_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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-Subparagraph (SX 210.5-02(22)(b))
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Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the required periodic payments of both interest and principal.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityPeriodicPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Balance Type:	credit
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- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as current. Excludes lease obligation.

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Balance Type:	credit
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- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

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-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

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Long-Term Debt, Finance Leases, and Other Borrowings - Additional Information (Detail)						1 Months Ended	3 Months Ended	9 Months Ended
	Mar. 18, 2025	Dec. 23, 2024	Sep. 06, 2023 USD ($)	Dec. 27, 2022 USD ($)	Oct. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) $ / shares	Sep. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Property and equipment-gross								$ 59,884,000			$ 329,619,000
Long-Term Debt								95,021,000			227,061,000
Current portion of long-term debt								$ 68,009,000			$ 143,275,000
Gain on investments							$ 1,578,000		$ 8,032,000
Warrants of common stock exercise price \| $ / shares								$ 3.98
Treasury Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Calculated collateral coverage ratio					1.55
Treasury Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Additional collateral coverage ratio					1.55
Loan Agreement [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of common stock \| shares					4,899,497
Warrants of common stock exercise price \| $ / shares					$ 3.98
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Permitted amount to redraw from existing credit facility			$ 7,900,000
Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Revolving commitments			50,700,000
Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Revolving commitments			$ 30,700,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate			3.50%	3.50%
Revolving loan				$ 10,500,000
Covenant capping restricted payments				5,000,000
Revolving commitments				$ 30,700,000
Rental coverage ratio				1
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Amount required										$ 15,000,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate			4.50%	4.50%
United Capacity Purchase Agreement [Member] \| United [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Amount funded by company										$ 25,500,000
Secured Term Loan Facility [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Secured term loan facility, maximum borrowing capacity					$ 200,000,000.0
Debt instrument, maturity date								Oct. 30, 2025
Secured Term Loan Facility [Member] \| Loan Agreement [Member] \| Treasury Loan [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate					3.50%
Percentage of all in rate								8.08%
Secured term loan facility, amount borrowed												$ 195,000,000.0
Secured term loan facility, additional amount borrowed								$ 0
Debt instrument, maturity date					Oct. 30, 2025
UST Loan [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date								Oct. 30, 2025
UST Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Minimum Collateral Coverage Ratio 1	91	99
E175 Aircraft [Member]
Debt Instrument [Line Items]
Remaining Balance						$ 73,400,000
Aircraft and Equipment [Member] \| Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment-gross								$ 47,000,000