Regulatory Matters (Information On The Capital Ratios) (Detail) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,804,290	$ 2,543,131
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,076,871	$ 1,008,512
Common Equity Tier One Capital Ratio	0.1172	0.1135
Common Equity Tier One Capital Required to be Well-Capitalized	$ 1,555,480	$ 1,456,739
Total risk-based capital, Actual Amount	$ 3,265,064	$ 3,045,652
Total risk-based capital, Actual Ratio	0.1364	0.1359
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,914,436	$ 1,792,910
Total risk-based capital, Capital Requirements, Minimum Ratio	0.080	0.080
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 2,393,046	$ 2,241,137
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	0.100	0.100
Tier 1 risk-based capital, Actual Amount	$ 2,949,327	$ 2,688,168
Tier 1 risk-based capital, Actual Ratio	0.1232	0.1199
Tier 1 risk-based capital, Capital Requirements, Minimum Amount	$ 1,435,827	$ 1,344,682
Tier 1 risk-based capital, Capital Requirements, Minimum Ratio	0.060	0.060
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,914,436	$ 1,792,910
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Ratio	0.080	0.080
Tier 1 leverage capital, Actual Amount	$ 2,949,327	$ 2,688,168
Tier 1 leverage capital, Actual Ratio	0.0847	0.0832
Tier 1 leverage capital, Capital Requirements, Minimum Amount	$ 1,393,607	$ 1,291,980
Tier 1 leverage capital, Capital Requirements, Minimum Ratio	0.040	0.040
Tier 1 leverage capital, Capital Requirements, Well Capitalized Amount	$ 1,742,008	$ 1,614,975
Tier 1 leverage capital, Capital Requirements, Well Capitalized Ratio	0.050	0.050
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 3,034,883	$ 2,791,474
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,075,920	$ 1,008,027
Common Equity Tier One Capital Ratio	0.1269	0.1246
Common Equity Tier One Capital Required to be Well-Capitalized	$ 1,554,107	$ 1,456,039
Total risk-based capital, Actual Amount	$ 3,273,300	$ 3,071,505
Total risk-based capital, Actual Ratio	0.1369	0.1371
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,912,747	$ 1,792,048
Total risk-based capital, Capital Requirements, Minimum Ratio	0.080	0.080
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 2,390,934	$ 2,240,060
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	0.100	0.100
Tier 1 risk-based capital, Actual Amount	$ 3,034,883	$ 2,791,474
Tier 1 risk-based capital, Actual Ratio	0.1269	0.1246
Tier 1 risk-based capital, Capital Requirements, Minimum Amount	$ 1,434,560	$ 1,344,036
Tier 1 risk-based capital, Capital Requirements, Minimum Ratio	0.060	0.060
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,912,747	$ 1,792,048
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Ratio	0.080	0.080
Tier 1 leverage capital, Actual Amount	$ 3,034,883	$ 2,791,474
Tier 1 leverage capital, Actual Ratio	0.0872	0.0865
Tier 1 leverage capital, Capital Requirements, Minimum Amount	$ 1,392,821	$ 1,291,415
Tier 1 leverage capital, Capital Requirements, Minimum Ratio	0.040	0.040
Tier 1 leverage capital, Capital Requirements, Well Capitalized Amount	$ 1,741,026	$ 1,614,268
Tier 1 leverage capital, Capital Requirements, Well Capitalized Ratio	0.050	0.050
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	0.045	0.045
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets [Member] | Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	0.045	0.045
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	0.065	0.065
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets [Member] | Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	0.065	0.065