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Derivatives (Derivatives Not Designated as Hedging Instruments - Credit Contracts) (Details) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Derivative [Line Items] |  |
Derivative assets - Fair value | $ 588,582 | $ 602,754
Derivative liabilities - Fair value | 448,921 | 424,828
Derivatives not designated as hedging instruments |  |
Derivative [Line Items] |  |
Notional Amount | 21,676,672 | 21,341,158
Derivative assets - Fair value | 588,582 | 602,754
Derivative liabilities - Fair value | 447,542 | 422,729
Credit contracts | Derivatives not designated as hedging instruments | Other credit derivatives |  |
Derivative [Line Items] |  |
Notional Amount | 83,693 | 76,992
Derivative assets - Fair value | 3 | 13
Derivative liabilities - Fair value | 87 | 206
Credit contracts | Derivatives not designated as hedging instruments | Other credit derivatives | RPAs - protection sold |  |
Derivative [Line Items] |  |
Notional Amount | 72,979 | 66,278
Derivative assets - Fair value | 0 | 0
Derivative liabilities - Fair value | 87 | 206
Credit contracts | Derivatives not designated as hedging instruments | Other credit derivatives | RPAs - protection purchased |  |
Derivative [Line Items] |  |
Notional Amount | 10,714 | 10,714
Derivative assets - Fair value | 3 | 13
Derivative liabilities - Fair value | $ 0 | $ 0

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