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Assets Held for Sale - Additional Information (Detail) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Apr. 03, 2025 Engine | Sep. 30, 2024 USD ($) Airframes Engines AirCraft | Sep. 30, 2023 USD ($) AirCraft | Sep. 30, 2022 USD ($)
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Asset impairment |  | $ 73,709 | $ 54,343 | $ 171,824
Impairment loss held for sale |  | 73,700 | 50,600 | $ 62,100
Aircraft held for sale current |  | $ 5,741 | 57,722 |
Number of aircraft split up to airframes | Airframes |  | 7 |  |
Number of aircraft split up to engines | Engines |  | 14 |  |
Aircraft held for sale |  | $ 86,605 | $ 12,000 |
Number of engines to be sold | Engines |  | 55 |  |
Number of airframes to be sold | Airframes |  | 26 |  |
Current Assets [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Aircraft held for sale current |  | $ 5,700 |  |
Noncurrent Assets [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Aircraft held for sale |  | $ 86,600 |  |
Without Active Purchase Agreement [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of engines to be sold | Engines |  | 19 |  |
Number of airframes to be sold | Airframes |  | 26 |  |
Subsequent Event [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of engines to be sold | Engine | 23 |  |  |
CRJ-900 [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft held for sale | AirCraft |  | 8 | 15 |
Number of airframes without engines | AirCraft |  | 26 |  |
Number of aircraft sold | AirCraft |  | 15 |  |
Gross proceeds from sale of asset |  | $ 71,500 |  |
Number of aircraft split up | AirCraft |  | 7 |  |
Aircraft held for sale |  | $ 92,300 |  |
GE Model [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft held for sale | AirCraft |  | 77 |  |
Airframes [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft held for sale | Airframes |  | 26 |  |
Airframes [Member] | RASPRO Aircraft Lease Agreement [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Airframes |  | 15 |  |
Gross proceeds from sale of asset |  | $ 18,800 |  |
Engines [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft held for sale | Engines |  | 55 |  |
Number of aircraft sold | Engines |  | 30 |  |
Gross proceeds from sale of asset |  | $ 19,500 |  |
29 Enginers [Member] | RASPRO Aircraft Lease Agreement [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 29 |  |
Gross proceeds from sale of asset |  | $ 18,900 |  |
Remaining Engine [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Gross proceeds from sale of asset |  | $ 700 |  |
23 Engines [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 23 |  |
Gross proceeds from sale of asset |  | $ 11,500 |  |
3 Engines [Member] | UST Loan [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 3 |  |
Gross proceeds from sale of asset |  | $ 1,500 |  |
12 Engines [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 12 |  |
Gross proceeds from sale of asset |  | $ 54,200 |  |
14 Enginers [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 14 |  |
Gross proceeds from sale of asset |  | $ 24,700 |  |
9 Enginers [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 9 |  |
Gross proceeds from sale of asset |  | $ 8,800 |  |
8 Enginers [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft sold | Engines |  | 8 |  |
Gross proceeds from sale of asset |  | $ 12,900 |  |
Proceeds from sale of asset |  | $ 4,400 |  |
CRJ-700 [Member] |  |  |  |
Long Lived Assets Held For Sale [Line Items] |  |  |  |
Number of aircraft held for sale | AirCraft |  | 2 |  |
Gross proceeds from sale of asset |  | $ 11,000 |  |

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