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Financial Derivative Instruments - Narrative (Details) $ in Millions | 6 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 30, 2021 USD ($) | Dec. 31, 2020 USD ($) aircraft | Mar. 31, 2021 aircraft | Dec. 31, 2019 aircraft
Derivative [Line Items] |  |  |  |
Net unrealized losses, net of taxes | $ (88) |  |  |
Number of aircraft leases | aircraft |  | 3 | 8 |
Aircraft lease term | 9 years |  |  |
Aircraft lease term | 9 years |  |  |
Remaining AOCI associated with future aircraft deliveries | $ 60 |  |  |
Interest rate derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Cash collateral held (from) by CP | $ 0 |  |  |
Interest rate derivatives | Cash Flow Hedging | Fuel and oil |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative deferred taxes |  | $ 0 |  |
Interest rate swap |  |  |  |
Derivative [Line Items] |  |  |  |
Number of aircraft leases | aircraft |  |  |  | 12

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