Regulatory Capital - U.S. Basel III Regulatory Requirements (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Actual Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 3,190,257	$ 3,579,005
Tier 1 Capital (to Risk-Weighted Assets)	3,190,257	3,579,005
Total Capital (to Risk-Weighted Assets)	3,276,009	3,849,820
Tier 1 Capital (to Average Assets)	$ 3,190,257	$ 3,579,005
Actual Ratio
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	13.70%	14.00%
Tier 1 Capital (to Risk-Weighted Assets)	0.137	0.140
Total Capital (to Risk-Weighted Assets)	0.140	0.150
Tier 1 Capital (to Average Assets)	0.105	0.113
Advanced Approach
U.S. Basel III Regulatory Requirements, Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 1,636,018	$ 1,794,780
Tier 1 Capital (to Risk-Weighted Assets)	1,986,593	2,179,375
Total Capital (to Risk-Weighted Assets)	2,454,027	2,692,169
Tier 1 Capital (to Average Assets)	$ 1,218,407	$ 1,264,424
U.S. Basel III Regulatory Requirements, Ratio
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	7.00%	7.00%
Tier 1 Capital (to Risk-Weighted Assets)	0.085	0.085
Total Capital (to Risk-Weighted Assets)	0.105	0.105
Tier 1 Capital (to Average Assets)	0.040	0.040

Common Equity Tier One Risk Based Capital

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Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets

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Tier One Common Equity Capital to Risk Weighted Assets

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Tier One Risk Based Capital for Common Equity Required to be Capitalized

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Amount of total capital as defined by regulatory framework.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

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Amount of Tier 1 leverage capital as defined by regulatory framework.

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