Securities - Summary Of Fair Value Of Available For Sale Securities By Contractual Maturities (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
AFS securities
Due in one year or less, Amortized Cost	$ 311	$ 1,512
Due in one year or less, Fair value	309	1,494
Due after one year to five years, Amortized Cost	485,444	1,211,778
Due after one year to five years, Fair value	441,553	1,074,080
Due after five to ten years, Amortized Cost	624,126	1,643,641
Due after five to ten years, Fair value	543,161	1,430,761
Due after ten years, Amortized Cost	4,248,408	4,968,504
Due after ten years, Fair value	3,535,270	4,184,443
Amortized Cost	5,358,289	7,825,435
Fair Value	4,520,293	6,690,778
HTM securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	0	0
Due after one year to five years, Fair value	0	0
Due after five to ten years, Amortized Cost	198,921	200,154
Due after five to ten years, Fair value	174,725	176,883
Due after ten years, Amortized Cost	266,140	276,493
Due after ten years, Fair value	238,139	246,343
Amortized Cost	465,061	476,647
Fair Value	412,864	423,226
Total
Due in one year or less, Amortized Cost	311	1,512
Due in one year or less, Fair value	309	1,494
Due after one year to five years, Amortized Cost	485,444	1,211,778
Due after one year to five years, Fair value	441,553	1,074,080
Due after five to ten years, Amortized Cost	823,047	1,843,795
Due after five to ten years, Fair value	717,886	1,607,644
Due after ten years, Amortized Cost	4,514,548	5,244,997
Due after ten years, Fair value	3,773,409	4,430,786
Amortized Cost	5,823,350	8,302,082
Fair Value	4,933,157	7,114,004
Government-sponsored residential mortgage-backed securities
AFS securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	20,580	21,221
Due after one year to five years, Fair value	19,521	20,284
Due after five to ten years, Amortized Cost	38,751	727,908
Due after five to ten years, Fair value	35,949	648,132
Due after ten years, Amortized Cost	3,411,396	4,106,634
Due after ten years, Fair value	2,835,594	3,443,492
Amortized Cost	3,470,727	4,855,763
Fair Value	2,891,064	4,111,908
HTM securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	0	0
Due after one year to five years, Fair value	0	0
Due after five to ten years, Amortized Cost	0	0
Due after five to ten years, Fair value	0	0
Due after ten years, Amortized Cost	266,140	276,493
Due after ten years, Fair value	238,139	246,343
Amortized Cost	266,140	276,493
Fair Value	238,139	246,343
Government-sponsored commercial mortgage-backed securities
AFS securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	135,485	191,762
Due after one year to five years, Fair value	121,687	171,992
Due after five to ten years, Amortized Cost	507,668	649,659
Due after five to ten years, Fair value	435,327	556,641
Due after ten years, Amortized Cost	711,034	728,698
Due after ten years, Fair value	583,146	620,321
Amortized Cost	1,354,187	1,570,119
Fair Value	1,140,160	1,348,954
HTM securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	0	0
Due after one year to five years, Fair value	0	0
Due after five to ten years, Amortized Cost	198,921	200,154
Due after five to ten years, Fair value	174,725	176,883
Due after ten years, Amortized Cost	0	0
Due after ten years, Fair value	0	0
Amortized Cost	198,921	200,154
Fair Value	174,725	176,883
U.S. Agency bonds
AFS securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	201,915	877,371
Due after one year to five years, Fair value	180,538	767,464
Due after five to ten years, Amortized Cost	33,929	223,520
Due after five to ten years, Fair value	29,532	185,018
Due after ten years, Amortized Cost	0	0
Due after ten years, Fair value	0	0
Amortized Cost	235,844	1,100,891
Fair Value	210,070	952,482
U.S. Treasury securities
AFS securities
Due in one year or less, Amortized Cost	0	0
Due in one year or less, Fair value	0	0
Due after one year to five years, Amortized Cost	99,437	99,324
Due after one year to five years, Fair value	93,082	93,057
Due after five to ten years, Amortized Cost	0	0
Due after five to ten years, Fair value	0	0
Due after ten years, Amortized Cost	0	0
Due after ten years, Fair value	0	0
Amortized Cost	99,437	99,324
Fair Value	93,082	93,057
State and municipal bonds and obligations
AFS securities
Due in one year or less, Amortized Cost	211	213
Due in one year or less, Fair value	209	209
Due after one year to five years, Amortized Cost	28,027	22,100
Due after one year to five years, Fair value	26,725	21,283
Due after five to ten years, Amortized Cost	43,778	42,554
Due after five to ten years, Fair value	42,353	40,970
Due after ten years, Amortized Cost	125,978	133,172
Due after ten years, Fair value	116,530	120,630
Amortized Cost	197,994	198,039
Fair Value	185,817	183,092
Other debt securities
AFS securities
Due in one year or less, Amortized Cost	100	1,299
Due in one year or less, Fair value	100	1,285
Due after one year to five years, Amortized Cost	0	0
Due after one year to five years, Fair value	0	0
Due after five to ten years, Amortized Cost	0	0
Due after five to ten years, Fair value	0	0
Due after ten years, Amortized Cost	0	0
Due after ten years, Fair value	0	0
Amortized Cost	100	1,299
Fair Value	$ 100	$ 1,285