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Subsequent Events - Additional Information (Detail) $ / shares in Units, $ in Thousands |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 24, 2025 USD ($) | Apr. 04, 2025 USD ($) Engine | Apr. 03, 2025 USD ($) Engine AirCraft | Mar. 18, 2025 | Jan. 31, 2025 USD ($) AirCraft | Jan. 01, 2025 USD ($) Airframes | Dec. 31, 2024 USD ($) Airframes Engines $ / shares shares | Dec. 31, 2023 USD ($) | Sep. 30, 2024 USD ($) $ / shares shares | Sep. 30, 2023 USD ($) $ / shares shares | Sep. 30, 2022 USD ($)
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding | shares |  |  |  |  |  |  | 41,331,719 |  | 41,331,719 | 40,940,326 |
Common stock, shares authorized | shares |  |  |  |  |  |  | 125,000,000 |  | 125,000,000 | 125,000,000 |
Common stock, no par value | $ / shares |  |  |  |  |  |  | $ 0 |  | $ 0 | $ 0 |
Net (loss) income |  |  |  |  |  |  | $ 111,944 | $ 57,850 | $ 91,015 | $ 120,116 | $ 182,678
Impairment loss |  |  |  |  |  |  | $ 4,900 | $ 40,400 | $ 73,700 | $ 50,600 | $ 62,100
Number of engines to be sold | Engines |  |  |  |  |  |  | 51 |  |  |  |
CRJ-900 Airframes [Member] | Airframe Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sold | Airframes |  |  |  |  |  |  | 25 |  |  |  |
CF34-8C Engines [Member] | Airframe Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sold | Airframes |  |  |  |  |  |  | 5 |  |  |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from sale of asset |  | $ 9,200 |  |  |  |  |  |  |  |  |
Percentage of increase in CPA block hour rates |  | 3.00% |  |  |  |  |  |  |  |  |
Number of engines to be sold | Engine |  |  | 23 |  |  |  |  |  |  |  |
Number of engine sold | Engine |  | 13 |  |  |  |  |  |  |  |  |
Remaining balance |  |  |  |  | $ 73,400 |  |  |  |  |  |
Subsequent Event [Member] | United Capacity Purchase Agreement [Member] | United Airlines, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Common stock issued equivalent percentage of issued and outstanding capital stock |  | 6.00% |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Engines Held For Sale [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Impairment loss |  |  | $ 14,700 |  |  | $ 38,800 |  |  |  |  |
Subsequent Event [Member] | E-175 Aircraft [Member] | United Aircraft Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Expected gross proceeds from sale of asset |  |  |  |  | $ 49,400 |  |  |  |  |  |
Expected proceeds from sale of asset |  |  | $ 16,300 |  |  |  |  |  |  |  |
Number of aircraft classified as assets held for sale | AirCraft |  |  |  |  | 10 |  |  |  |  |  |
Gross proceeds from sale of asset |  |  |  |  | $ 122,900 |  |  |  |  |  |
Number of aircraft sold | AirCraft |  |  | 23 |  |  |  |  |  |  |  |
Net (loss) income |  |  |  |  | $ 7,300 |  |  |  |  |  |
Subsequent Event [Member] | CRJ-900 Airframes [Member] | Airframe Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from sale of asset |  |  | $ 9,100 |  |  |  |  |  |  |  |
Number of aircraft sold |  |  | 14 |  |  | 28 |  |  |  |  |
Subsequent Event [Member] | CF34-8C Engines [Member] | Airframe Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sold | Airframes |  |  |  |  |  | 5 |  |  |  |  |
Subsequent Event [Member] | UST Loan [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Minimum collateral coverage ratio |  |  |  | 0.91 |  |  |  |  |  |  |
Subsequent Event [Member] | UST Loan [Member] | Aircraft Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from sale of asset |  |  |  |  |  | $ 67,000 |  |  |  |  |
Repayments of debt |  |  |  |  |  | $ 62,400 |  |  |  |  |
Subsequent Event [Member] | Secured Term Loan Facility [Member] | Loan Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |
Interest rate under the Loan Agreement | 0.00% |  |  |  |  |  |  |  |  |  |
Principal amount of the Obligation | $ 12,300 |  |  |  |  |  |  |  |  |  |
Amount deposited in collateral account | 31,900 |  |  |  |  |  |  |  |  |  |
Non-refundable advisory fee | $ 3,500 |  |  |  |  |  |  |  |  |  |

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