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Investments - Additional Information (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 USD ($) engine aircraft. | Dec. 31, 2019 USD ($)
Schedule of Equity Method Investments [Line Items] |  |
Ownership interest | 50.00% |
Net book value of equipment held for operating lease | $ 31,753 | $ 31,520
Assets Leased to Others |  |
Schedule of Equity Method Investments [Line Items] |  |
Net book value of equipment held for operating lease | $ 1,886,613 | 1,650,918
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 | Other Revenue |  |
Schedule of Equity Method Investments [Line Items] |  |
Management fees earned | $ 1,600 | $ 2,900
WMES | Assets Leased to Others |  |
Schedule of Equity Method Investments [Line Items] |  |
Net book value of equipment held for operating lease | $ 289,200 |
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 | $ 50,100 |

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