Regulatory Capital - U.S. Basel III Regulatory Requirements (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Actual Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 2,992,368	$ 2,957,067
Tier 1 Capital (to Risk-Weighted Assets)	2,992,368	2,957,067
Total Capital (to Risk-Weighted Assets)	3,329,485	3,294,663
Tier 1 Capital (to Average Assets)	$ 2,992,368	$ 2,957,067
Actual Ratio
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	11.60%	11.30%
Tier 1 Capital (to Risk-Weighted Assets)	0.116	0.113
Total Capital (to Risk-Weighted Assets)	0.129	0.126
Tier 1 Capital (to Average Assets)	0.101	0.097
U.S. Basel III Minimum Requirements Plus Buffer, Amount
Common Equity Tier 1 Capital (to Risk-Weighted Assets)	$ 1,808,123	$ 1,827,318
Tier 1 Capital (to Risk-Weighted Assets)	2,195,578	2,218,886
Total Capital (to Risk-Weighted Assets)	2,712,184	2,740,976
Tier 1 Capital (to Average Assets)	$ 1,185,745	$ 1,213,505
U.S. Basel III Minimum Requirements Plus Buffer, 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