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Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 | Jul. 31, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019 | Feb. 28, 2021
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |
Depreciation expense |  |  | $ 81,200 | $ 80,800 | $ 76,200 |
Estimated initial equity warrant asset value |  |  |  |  |  | $ 16,400
Warrant asset value | $ 16,400 |  | 16,400 |  |  |
Losses on investments |  |  | (6,816) |  |  |
Amortization of unfavorable lease liability |  |  |  |  | 5,718 |
Write off of unfavorable lease liability |  |  |  |  | $ 800 |
Archer Aviation, Inc. [Member] |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |
Losses on investments |  |  | $ (6,800) |  |  |
Heart Aerospace Incorporated [Member] | Forward Purchase Contract [Member] | Preferred Stock [Member] |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |
Purchase of preferred stock |  | $ 5,000 |  |  |  |
Initial investment in preferred stock measured at cost |  | $ 5,000 |  |  |  |
Class A [Member] | Archer Aviation, Inc. [Member] |  |  |  |  |  |
Condensed Balance Sheet Statements Captions [Line Items] |  |  |  |  |  |
Stock issued during period, Shares | 500,000 |  |  |  |  |
Stock issued during period, Value | $ 5,000 |  |  |  |  |
Total grant date value, Additional warrant to purchase shares | $ 5,600 |  |  |  |  |

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