Regulatory Capital and Restrictions - Schedule of Information on Capital Ratios (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2024 USD ($)	Dec. 31, 2025 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual, CET1 Risk-Based Capital	$ 6,318,876	$ 6,441,440
Actual, Tier 1 Risk-Based Capital	6,602,855	6,725,419
Actual, Total Risk-Based Capital	7,800,717	7,861,688
Actual, Tier 1 Leverage Capital	$ 6,602,855	$ 6,725,419
Ratio, CET1 Risk-Based Capital	0.1154	0.1120
Actual, Ratio, Tier 1 Risk-Based Capital	0.1206	0.1169
Ratio, Total Risk-Based Capital	0.1424	0.1367
Actual, Ratio, Tier 1 Leverage Capital	0.0870	0.0833
Minimum Requirement, CET1 Risk-Based Capital	$ 2,464,542	$ 2,588,039
Minimum Requirement, Tier 1 Risk-Based Capital	3,286,057	3,450,719
Minimum Requirement, Total Risk-Based Capital	4,381,409	4,600,959
Minimum Requirement, Tier 1, Leverage Capital	$ 3,034,369	$ 3,230,039
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	$ 3,738,279
Well Capitalized, Tier 1 Risk-Based Capital	4,381,409	4,600,959
Well Capitalized, Total Risk-Based Capital	5,476,761	5,751,199
Well Capitalized, Tier 1 Leverage Capital	$ 3,792,961	$ 4,037,549
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	$ 7,007,352
Actual, Tier 1 Risk-Based Capital	6,847,474	7,007,352
Actual, Total Risk-Based Capital	7,512,143	7,720,373
Actual, Tier 1 Leverage Capital	$ 6,847,474	$ 7,007,352
Ratio, CET1 Risk-Based Capital	0.1253	0.1219
Actual, Ratio, Tier 1 Risk-Based Capital	0.1253	0.1219
Ratio, Total Risk-Based Capital	0.1374	0.1343
Actual, Ratio, Tier 1 Leverage Capital	0.0904	0.0869
Minimum Requirement, CET1 Risk-Based Capital	$ 2,460,031	$ 2,586,346
Minimum Requirement, Tier 1 Risk-Based Capital	3,280,042	3,448,461
Minimum Requirement, Total Risk-Based Capital	4,373,389	4,597,948
Minimum Requirement, Tier 1, Leverage Capital	$ 3,031,190	$ 3,226,561
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	$ 3,735,833
Well Capitalized, Tier 1 Risk-Based Capital	4,373,389	4,597,948
Well Capitalized, Total Risk-Based Capital	5,466,736	5,747,435
Well Capitalized, Tier 1 Leverage Capital	$ 3,788,988	$ 4,033,202
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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