XML 66 R54.htm IDEA: XBRL DOCUMENT v3.20.2

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Income Taxes [Line Items]
Effective tax rate (ETR) from continuing operations	30.70%	22.20%	28.30%	23.60%
State net operating loss carryforwards					$ 2.7
Domestic Tax Authority [Member] | 2027-2037 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					478.3
State and Local Jurisdiction [Member] | 2020-2039 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					$ 228.3
Minimum [Member] | Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2027
Minimum [Member] | State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2020
Maximum [Member] | Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2037
Maximum [Member] | State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2039

X

- Definition

Income Taxes [Line Items]

+ References

No definition available.

+ Details

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

X

- Definition

Operating loss carryforwards expiration year.

+ References

No definition available.

+ Details

Name:	mesa_OperatingLossCarryforwardsExpirationYear
Namespace Prefix:	mesa_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

+ Details

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

X

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates.

+ References

No definition available.

+ Details

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

X

- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_TaxPeriodAxis=mesa_PeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_TaxPeriodAxis=mesa_PeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: