Regulatory Capital and Restrictions (Information On The Capital Ratios) (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 risk-based capital, Actual Amount	$ 5,923,041		$ 6,188,433
CET1 risk-based capital, Actual Ratio	0.1057		0.1111
CET1 risk-based capital, Minimum Requirement Amount	$ 2,521,412		$ 2,507,190
CET1 risk-based capital, Well Capitalized Amount	3,642,040		3,621,497
Total risk-based capital, Actual Amount	$ 7,400,017		$ 7,643,423
Total risk-based capital, Actual Ratio	0.1321		0.1372
Total risk-based capital, Capital Requirements, Minimum Amount	$ 4,482,510		$ 4,457,227
Total risk-based capital, Capital Requirements, Minimum Ratio	0.080		0.080
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 5,603,138		$ 5,571,534
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	0.100		0.100
Tier 1 capital, Actual Amount	$ 6,207,020		$ 6,472,412
Tier 1 capital, Actual Ratio	0.1108		0.1162
Tier 1 capital, Capital Requirements, Minimum Amount	$ 3,361,883		$ 3,342,920
Tier 1 capital, Capital Requirements, Minimum Ratio	0.060		0.060
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 4,482,510		$ 4,457,227
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	0.080		0.080
Tier 1 leverage capital ratio, Actual Amount	$ 6,207,020		$ 6,472,412
Tier 1 leverage capital ratio, Actual Ratio	0.0851		0.0906
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 2,916,558		$ 2,857,890
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	0.040		0.040
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	$ 3,645,697		$ 3,572,362
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	0.050		0.050
Dividends paid	$ 175,000	$ 150,000
Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 risk-based capital, Actual Amount	$ 6,588,389		$ 6,913,443
CET1 risk-based capital, Actual Ratio	0.1178		0.1243
CET1 risk-based capital, Minimum Requirement Amount	$ 2,516,948		$ 2,502,835
CET1 risk-based capital, Well Capitalized Amount	3,635,591		3,615,206
Total risk-based capital, Actual Amount	$ 7,191,796		$ 7,494,332
Total risk-based capital, Actual Ratio	0.1286		0.1347
Total risk-based capital, Capital Requirements, Minimum Amount	$ 4,474,574		$ 4,449,484
Total risk-based capital, Capital Requirements, Minimum Ratio	0.080		0.080
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 5,593,217		$ 5,561,855
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	0.100		0.100
Tier 1 capital, Actual Amount	$ 6,588,389		$ 6,913,443
Tier 1 capital, Actual Ratio	0.1178		0.1243
Tier 1 capital, Capital Requirements, Minimum Amount	$ 3,355,930		$ 3,337,113
Tier 1 capital, Capital Requirements, Minimum Ratio	0.060		0.060
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 4,474,574		$ 4,449,484
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	0.080		0.080
Tier 1 leverage capital ratio, Actual Amount	$ 6,588,389		$ 6,913,443
Tier 1 leverage capital ratio, Actual Ratio	0.0904		0.0969
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 2,913,783		$ 2,855,212
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	0.040		0.040
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	$ 3,642,229		$ 3,569,015
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	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]
CET1 risk-based capital, Actual Ratio	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]
CET1 risk-based capital, Actual Ratio	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]
CET1 risk-based capital, Actual Ratio	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]
CET1 risk-based capital, Actual Ratio	0.065		0.065

Amount of total capital as defined by regulatory framework.

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Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

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Amount of Common Equity Tier 1 risk-based capital as defined by regulatory framework.

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Amount of minimum Common Equity Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

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Amount of minimum Common Equity Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

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

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