Regulatory Capital and Restrictions - Schedule of Information on Capital Ratios (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2024 USD ($)	Mar. 31, 2025 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual, CET1 Risk-Based Capital	$ 6,318,876	$ 6,276,086
Actual, Tier 1 Risk-Based Capital	6,602,855	6,560,065
Actual, Total Risk-Based Capital	7,800,717	7,788,501
Actual, Tier 1 Leverage Capital	$ 6,602,855	$ 6,560,065
Ratio, CET1 Risk-Based Capital	0.1154	0.1125
Actual, Ratio, Tier 1 Risk-Based Capital	0.1206	0.1176
Ratio, Total Risk-Based Capital	0.1424	0.1396
Actual, Ratio, Tier 1 Leverage Capital	0.0870	0.0854
Minimum Requirement, CET1 Risk-Based Capital	$ 2,464,542	$ 2,510,372
Minimum Requirement, Tier 1 Risk-Based Capital	3,286,057	3,347,163
Minimum Requirement, Total Risk-Based Capital	4,381,409	4,462,884
Minimum Requirement, Tier 1, Leverage Capital	$ 3,034,369	$ 3,072,950
Minimum Requirement, Ratio, Tier 1 Risk-Based Capital	0.060	0.060
Minimum Requirement, Ratio, Total Risk-Based Capital	0.080	0.080
Minimum Requirement, Ratio, Tier 1 Leverage Capital	0.040	0.040
Well Capitalized, CET1 Risk-Based Capital	$ 3,559,895	$ 3,626,093
Well Capitalized, Tier 1 Risk-Based Capital	4,381,409	4,462,884
Well Capitalized, Total Risk-Based Capital	5,476,761	5,578,605
Well Capitalized, Tier 1 Leverage Capital	$ 3,792,961	$ 3,841,187
Well Capitalized, Ratio, Tier 1 Risk-Based Capital	0.080	0.080
Well Capitalized, Ratio, Total Risk-Based Capital	0.100	0.100
Well Capitalized, Ratio, Tier 1 Leverage Capital	0.050	0.050
Transition regulatory capital percentage	25.00%
Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual, CET1 Risk-Based Capital	$ 6,847,474	$ 6,988,372
Actual, Tier 1 Risk-Based Capital	6,847,474	6,988,372
Actual, Total Risk-Based Capital	7,512,143	7,684,411
Actual, Tier 1 Leverage Capital	$ 6,847,474	$ 6,988,372
Ratio, CET1 Risk-Based Capital	0.1253	0.1256
Actual, Ratio, Tier 1 Risk-Based Capital	0.1253	0.1256
Ratio, Total Risk-Based Capital	0.1374	0.1381
Actual, Ratio, Tier 1 Leverage Capital	0.0904	0.0911
Minimum Requirement, CET1 Risk-Based Capital	$ 2,460,031	$ 2,504,775
Minimum Requirement, Tier 1 Risk-Based Capital	3,280,042	3,339,701
Minimum Requirement, Total Risk-Based Capital	4,373,389	4,452,934
Minimum Requirement, Tier 1, Leverage Capital	$ 3,031,190	$ 3,069,811
Minimum Requirement, Ratio, Tier 1 Risk-Based Capital	0.060	0.060
Minimum Requirement, Ratio, Total Risk-Based Capital	0.080	0.080
Minimum Requirement, Ratio, Tier 1 Leverage Capital	0.040	0.040
Well Capitalized, CET1 Risk-Based Capital	$ 3,553,378	$ 3,618,009
Well Capitalized, Tier 1 Risk-Based Capital	4,373,389	4,452,934
Well Capitalized, Total Risk-Based Capital	5,466,736	5,566,168
Well Capitalized, Tier 1 Leverage Capital	$ 3,788,988	$ 3,837,264
Well Capitalized, Ratio, Tier 1 Risk-Based Capital	0.080	0.080
Well Capitalized, Ratio, Total Risk-Based Capital	0.100	0.100
Well Capitalized, Ratio, Tier 1 Leverage Capital	0.050	0.050
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio, CET1 Risk-Based Capital	0.045	0.045
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets \| Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio, CET1 Risk-Based Capital	0.045	0.045
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio, CET1 Risk-Based Capital	0.065	0.065
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets \| Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio, CET1 Risk-Based Capital	0.065	0.065

Amount of total capital as defined by regulatory framework.

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