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Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail) |  | 1 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
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Sep. 25, 2019 USD ($) | Jul. 31, 2022 Air-craft | Jun. 30, 2022 USD ($) | Dec. 31, 2021 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) Airfleet | Jan. 31, 2019 USD ($) | Feb. 28, 2018 Engine | Jun. 30, 2022 USD ($) | Sep. 30, 2021 | Sep. 30, 2016 USD ($) Air-craft | Sep. 30, 2015 USD ($) Air-craft | Nov. 14, 2020 USD ($) | Nov. 13, 2020 USD ($) | Oct. 31, 2020 USD ($) | Oct. 30, 2020 USD ($)
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2027 | 2027 |  |  |  |  |  |
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member] | CRJ-900 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft financed | Air-craft |  |  |  |  |  |  |  |  |  |  |  | 7 |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  |  | $ 170,200,000 |  |  |  |
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2028 | 2028 |  |  |  |  |  |
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft financed | Air-craft |  |  |  |  |  |  |  |  |  |  | 10 |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  | $ 246,000,000.0 |  |  |  |  |
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate percentage |  |  | 4.75% |  |  |  |  |  | 4.75% |  |  |  |  |  |  |
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate percentage |  |  | 6.25% |  |  |  |  |  | 6.25% |  |  |  |  |  |  |
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2028 | 2028 |  |  |  |  |  |
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Eight E-175 Aircraft [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  | $ 195,300,000 |  |  |  |  |
Number of aircraft refinanced | Air-craft |  |  |  |  |  |  |  |  |  |  | 8 |  |  |  |  |
Other Obligations Due to Financial Institutions, Collateralized by the Underlying Equipment, Due 2024 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2024 | 2024 |  |  |  |  |  |
Other Obligations Due to Financial Institutions, Collateralized by the Underlying Equipment, Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2023 | 2023 |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2024 | 2024 |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] | Flight Equipment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  | $ 91,200,000 |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | monthly LIBOR plus 3.10% |  |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] | LIBOR [Member] | Flight Equipment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  | 3.10% |  |  |  |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2023 | 2023 |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] | CRJ-700 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft financed | Airfleet |  |  |  |  |  | 10 |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | $ 70,000,000.0 |  |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | monthly LIBOR plus 5.00% |  |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] | CRJ-700 Aircraft [Member] | LIBOR [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  | 5.00% |  |  |  |  |  |  |  |  |  |
Notes Payable to Financial Institution Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2023 | 2023 |  |  |  |  |  |
Notes Payable to Financial Institution Due 2023 [Member] | Flight Equipment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | $ 8,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | monthly LIBOR plus 5.00% |  |  |  |  |  |  |
Notes Payable to Financial Institution Due 2023 [Member] | LIBOR [Member] | Flight Equipment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  |  |  | 5.00% |  |  |  |  |  |  |
Notes Payable to U.S Treasury Due 2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2025 | 2025 |  |  |  |  |  |
Notes Payable to U.S Treasury Due 2025 [Member] | Loan Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | three-month LIBOR plus 3.50% |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  |  |  | 3.50% |  |  |  |  |  |  |
Secured term loan facility, maximum borrowing capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 200,000,000.0 |
Secured term loan facility, amount borrowed |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 43,000,000.0
Secured term loan facility, additional amount borrowed |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 | $ 152,000,000.0 |  |
Debt instrument, maturity date |  |  |  |  |  |  |  |  | Oct. 30, 2025 |  |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2027 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument maturity year |  |  |  |  |  |  |  |  | 2027 | 2027 |  |  |  |  |  |
Debt instrument, face amount |  |  | $ 35,300,000 | $ 35,300,000 |  |  |  |  | $ 35,300,000 |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | monthly LIBOR plus 4.25% |  |  |  |  |  |  |
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2027 [Member] | LIBOR [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  | 4.25% | 4.25% |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  |  | $ 154,700,000 |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | monthly LIBOR plus 2.71% |  |  |  |  |  |  |
Senior Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member] | LIBOR [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  |  | 2.71% |  |  |  |
Subordinated Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Imputed interest |  |  |  |  |  |  |  |  |  |  |  | 6.25% |  |  |  |
Debt discount |  |  |  |  |  |  |  |  |  |  |  | $ 8,100,000 |  |  |  |
Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | three-month LIBOR plus a spread ranging from 2.20% to 2.32% |  |  |  |  |  |  |
Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  | $ 172,000,000.0 |  |  |  |  |
Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | LIBOR [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  | 2.20% |  |  |  |  |
Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | LIBOR [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  | 2.32% |  |  |  |  |
Subordinated Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate percentage |  |  | 4.50% |  |  |  |  |  | 4.50% |  |  |  |  |  |  |
Other Obligations Due to Financial Institutions, Collateralized by the Underlying Equipment, Due 2023 and 2024 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Imputed interest |  |  |  |  |  |  |  | 9.13% |  |  |  |  |  |  |  |
Number of spare engines leased | Engine |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Other Obligations Due to Financial Institutions, Collateralized by the Underlying Equipment, Due 2023 and 2024 [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft leased | Air-craft |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Working Capital Draw Loan [Member] | Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount | $ 35,000,000.0 |  |  |  | $ 35,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Long term debt interest rate description |  |  |  |  |  |  |  |  | one-month LIBOR plus 3.75% |  |  |  |  |  |  |
Term loan, term | 3 years |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |
Debt instrument, expiration year and month | 2022-09 |  |  |  | 2022-12 |  |  |  |  |  |  |  |  |  |  |
Working Capital Draw Loan [Member] | LIBOR [Member] | Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long term debt, basis spread on variable rate | 3.75% |  |  |  | 3.75% |  |  |  |  |  |  |  |  |  |  |

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