Regulatory Capital - U.S. Basel III Regulatory Requirements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Actual Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 3,155,469	$ 3,314,657
Tier 1 Capital (to Risk-Weighted Assets)	3,155,469	3,314,657
Total Capital (to Risk-Weighted Assets)	3,462,126	3,410,183
Tier 1 Capital (to Average Assets)	$ 3,155,469	$ 3,314,657
Actual Ratio
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	12.90%	14.10%
Tier 1 Capital (to Risk-Weighted Assets)	0.129	0.141
Total Capital (to Risk-Weighted Assets)	0.142	0.145
Tier 1 Capital (to Average Assets)	0.105	0.111
U.S. Basel III Regulatory Requirements, Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 1,710,526	$ 1,643,132
Tier 1 Capital (to Risk-Weighted Assets)	2,077,067	1,995,232
Total Capital (to Risk-Weighted Assets)	2,565,789	2,464,699
Tier 1 Capital (to Average Assets)	$ 1,199,485	$ 1,198,808
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