Derivatives (Derivatives Not Designated as Hedging Instruments - Credit Contracts) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative assets - Fair value	$ 694,010	$ 602,754
Derivative liabilities - Fair value	561,788	424,828
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional Amount	20,874,985	21,341,158
Derivative assets - Fair value	693,852	602,754
Derivative liabilities - Fair value	560,639	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	15	13
Derivative liabilities - Fair value	120	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	120	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	15	13
Derivative liabilities - Fair value	$ 0	$ 0

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959

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