Number of aircraft lease terminated.

No definition available.

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Namespace Prefix:	mesa_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of leased aircraft.

+ References

No definition available.

+ Details

Name:	mesa_NumberOfLeasedAircraft
Namespace Prefix:	mesa_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

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+ Details

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

+ References

No definition available.

+ Details

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

- Definition

Weighted average discount rate for operating lease calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
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+ Details

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

- Definition

Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow for acquisition of long-lived depreciable flight assets, including owned aircraft or capital improvements.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=mesa_CRJ900AircraftMember
Namespace Prefix:
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Period Type:

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended			9 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Jun. 30, 2023 USD ($) AirCraft	Dec. 31, 2022 USD ($) AirCraft	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) AirCraft	Jun. 30, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Number of leased aircraft	18			18
Aggregate rental expense under all operating aircraft, equipment and facility leases \| $	$ 3,557		$ 10,845	$ 14,252	$ 33,070
Weighted average remaining lease term Operating leases	6 years 2 months 12 days			6 years 2 months 12 days
Weighted average discount rate Operating leases	5.30%			5.30%
RASPRO Aircraft Lease Agreement [Member]
Lessee, Lease, Description [Line Items]
Number of aircraft lease terminated		15
Buyout pricing \| $		$ 25,000
RASPRO Aircraft Lease Agreement [Member] \| CRJ-900 Aircraft [Member]
Lessee, Lease, Description [Line Items]
Number of leased aircraft		15