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Balance Sheet Information - Additional Information (Detail) |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jul. 01, 2024 USD ($) shares | Jan. 31, 2024 USD ($) | Sep. 30, 2021 USD ($) shares | Jul. 31, 2021 USD ($) | Jun. 30, 2024 USD ($) RotableParts Engine shares | Jun. 30, 2023 USD ($) | Mar. 31, 2024 Engine | Jun. 30, 2024 USD ($) Engine | Jun. 30, 2023 USD ($) | Sep. 30, 2023 USD ($) | Feb. 28, 2022 USD ($) | Feb. 28, 2021 USD ($)
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment true-up adjustment |  |  |  |  | $ 4,300,000 |  |  |  |  |  |  |
Number of engines held to sale | Engine |  |  |  |  | 13 |  | 66 | 64 |  |  |  |
Number of rotable parts | RotableParts |  |  |  |  | 737 |  |  |  |  |  |  |
Depreciation expense |  |  |  |  | $ 9,700,000 | $ 15,300,000 |  | $ 32,800,000 | $ 46,900,000 |  |  |
Estimated initial equity warrant asset value |  |  |  |  |  |  |  |  |  |  |  | $ 16,400,000
Number of shares sold | shares |  |  |  |  | 760,000 |  |  |  |  |  |  |
Proceeds from sale |  |  |  |  | $ 2,700,000 |  |  |  |  |  |  |
Total net unrealized gain/(loss) |  |  |  |  | (2,000,000) | 2,900,000 |  | (6,100,000) | 3,300,000 |  |  |
Estimated initial warrant asset value |  |  |  |  |  |  |  |  |  |  | $ 3,200,000 |
Investments in equity securities |  |  |  |  | 300,000 |  |  | 300,000 |  | $ 20,320,000 |  |
Total realized gain (loss) on equity securities |  |  |  |  | 6,500,000 | $ 0 |  | 6,500,000 | $ 0 |  |  |
Aggregate carrying amount of investments in equity securities |  |  |  |  | 5,700,000 |  |  | 5,700,000 |  | 20,300,000 |  |
Investments without readily determinable fair value |  |  |  |  | 300,000 |  |  | 300,000 |  | $ 8,800,000 |  |
United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Debt reduction |  | $ 12,600,000 |  |  |  |  |  |  |  |  |  |
Realized and unrealized gain (loss) on investment |  | $ 7,200,000 |  |  |  |  |  |  |  |  |  |
Engines Held For Sale [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment true-up adjustment |  |  |  |  | 5,700,000 |  |  |  |  |  |  |
Rotable Parts [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment true-up adjustment |  |  |  |  | $ 2,200,000 |  |  |  |  |  |  |
Archer Aviation, Inc. [Member] | Level 1 [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of shares sold | shares |  |  |  |  | 800,000 |  |  |  |  |  |  |
Proceeds from sale |  |  |  |  | $ 2,700,000 |  |  |  |  |  |  |
Loss on sale |  |  |  |  | 800,000 |  |  |  |  |  |  |
Realized and unrealized gain (loss) on investment |  |  |  |  | (1,700,000) |  |  | (2,700,000) |  |  |  |
Investments in equity securities |  |  |  |  | 5,300,000 |  |  | 5,300,000 |  |  |  |
VTOL Aircraft, XTI Aerospace, Inc [Member] | Level 1 [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Realized and unrealized gain (loss) on investment |  |  |  |  |  |  |  | (3,400,000) |  |  |  |
Investments in equity securities |  |  |  |  | $ 100,000 |  |  | $ 100,000 |  |  |  |
Heart Aerospace Incorporated [Member] | Forward Purchase Contract [Member] | Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Purchase of preferred stock |  |  |  | $ 5,000,000.0 |  |  |  |  |  |  |  |
Initial investment in preferred stock measured at cost |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |
Class A [Member] | Archer Aviation, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of shares sold | shares |  |  | 500,000 |  |  |  |  |  |  |  |  |
Proceeds from sale |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |
Total grant date value, Additional warrant to purchase shares |  |  | $ 5,600,000 |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Archer Aviation, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of shares sold | shares | 1,500,000 |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale | $ 6,900,000 |  |  |  |  |  |  |  |  |  |  |
Realized gain on sale of shares | $ 1,600,000 |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Archer Aviation, Inc. [Member] | Level 1 [Member] |  |  |  |  |  |  |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of shares sold | shares | 1,500,000 |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale | $ 6,900,000 |  |  |  |  |  |  |  |  |  |  |
Realized gain on sale of shares | $ 1,600,000 |  |  |  |  |  |  |  |  |  |  |

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