Concentration risk threshold percentage.

No definition available.

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- Definition

Number of vendors represents more than ten percentage of purchases.

+ References

No definition available.

+ Details

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

- Definition

Percentage of purchases during year.

+ References

No definition available.

+ Details

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

- Definition

Amount of allowance for credit loss on accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-4

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 310
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478785/954-310-50-2

+ Details

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

- Definition

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References

+ Details

Name:	us-gaap_RestrictedCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of cash restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-8

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_MajorCustomersAxis=mesa_AarMember
Namespace Prefix:
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Balance Type:
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- Details

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Data Type:	na
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- Details

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Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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- Details

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Concentrations of Credit Risk - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($)	Mar. 31, 2024	Sep. 30, 2024 USD ($) Vendor	Sep. 30, 2023 USD ($)	Sep. 30, 2022
Concentration Risk [Line Items]
Restricted cash	$ 3,043		$ 3,009	$ 3,132
Outstanding letters of credit to be collateralized by amounts on deposit	$ 3,000		3,000	3,100
Allowance for doubtful accounts			$ 0	$ 0
Number of vendors represents more than ten percentage of purchases \| Vendor			2
AAR {Member]
Concentration Risk [Line Items]
Percentage of purchases during year			18.00%
Standard Aero Holdings, Inc. [Member]
Concentration Risk [Line Items]
Percentage of purchases during year			11.00%
Sales Revenue, Net [Member] \| American Airlines Inc. [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			0.00%	23.00%	45.00%
Sales Revenue, Net [Member] \| United Airlines Inc [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	97.00%	98.00%	97.00%	73.00%	48.00%