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Investments - Additional Information (Details) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 USD ($) engine aircraft. | Mar. 31, 2020 USD ($) | Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |
Net book value of equipment held for operating lease | $ 31,169 |  | $ 31,753
Assets Leased to Others |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Net book value of equipment held for operating lease | $ 1,887,884 |  | $ 1,886,613
WMES |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership interest | 50.00% |  |
Number of engines in lease portfolio | engine | 36 |  |
Number of aircraft in lease portfolio | aircraft. | 5 |  |
WMES | Assets Leased to Others |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Net book value of equipment held for operating lease | $ 285,000 |  |
CASC Willis |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership interest | 50.00% |  |
Number of engines in lease portfolio | engine | 4 |  |
CASC Willis | Assets Leased to Others |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Net book value of equipment held for operating lease | $ 49,700 |  |
Other Income | WMES | Asset Management |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Maintenance reserve revenue | $ 300 | $ 500 |

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