XML 64 R50.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Earnings Per Share - Additional Information (Detail) - shares | 12 Months Ended
--- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Restricted Stock [Member] |  |  |
Earnings Per Share [Line Items] |  |  |
Anti-dilutive securities excluded from calculation of diluted loss per share | 0 | 0 | 0
Number of Warrants [Member] |  |  |
Earnings Per Share [Line Items] |  |  |
Anti-dilutive securities excluded from calculation of diluted loss per share | 0 | 0 | 0

X
- Definition Earnings Per Share [Line Items] + References No definition available. + Details
Name: | mesa_EarningsPerShareLineItems
Namespace Prefix: | mesa_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=us-gaap_RestrictedStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=us-gaap_WarrantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |