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Investments - Additional Information (Details) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 USD ($) | Sep. 30, 2020 USD ($) | Sep. 30, 2021 USD ($) equipment engine aircraft. | Sep. 30, 2020 USD ($) equipment noteReceivable | Dec. 31, 2020 USD ($)
Equipment Held For Operating Lease |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Net book value of equipment held for operating lease | $ 1,971,252 |  | $ 1,971,252 |  | $ 1,886,613
WMES |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership interest | 50.00% |  | 50.00% |  |
Number of engines in lease portfolio | engine |  |  | 37 |  |
Number of aircraft in lease portfolio | aircraft. |  |  | 5 |  |
Number of assets sold |  |  | 2 | 1 |
Proceeds from sale of assets |  |  | $ 25,000 | $ 8,400 |
WMES | Aircraft |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Net book value of equipment held for operating lease | $ 297,300 |  | $ 297,300 |  |
CASC Willis |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership interest | 50.00% |  | 50.00% |  |
Number of engines in lease portfolio | engine |  |  | 4 |  |
Number of assets sold | equipment |  |  | 0 | 0 |
CASC Willis | Equipment Held For Operating Lease |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Net book value of equipment held for operating lease | $ 48,900 |  | $ 48,900 |  |
Other Income | WMES | Asset Management |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Other sales and revenues | $ 900 | $ 400 | $ 1,600 | $ 1,200 |

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