Investment Securities - Summary of Securities Available for Sale in an Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	$ 810,689	$ 2,669,066
Less than 12 months, Unrealized Losses	21,169	209,141
12 months or longer, Fair Value	3,537,149	1,757,697
12 months or longer, Unrealized Losses	390,023	260,921
Total, Fair Value	4,347,838	4,426,763
Total, Unrealized Losses	411,192	470,062
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	180,725	473,025
Less than 12 months, Unrealized Losses	2,531	13,628
12 months or longer, Fair Value	343,241	48,793
12 months or longer, Unrealized Losses	12,608	5,299
Total, Fair Value	523,966	521,818
Total, Unrealized Losses	15,139	18,927
State and Political Subdivisions [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	69,465	496,328
Less than 12 months, Unrealized Losses	1,481	63,019
12 months or longer, Fair Value	623,467	192,234
12 months or longer, Unrealized Losses	88,651	47,654
Total, Fair Value	692,932	688,562
Total, Unrealized Losses	90,132	110,673
Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	122,666	623,587
Less than 12 months, Unrealized Losses	4,408	70,744
12 months or longer, Fair Value	1,033,590	550,135
12 months or longer, Unrealized Losses	169,256	123,787
Total, Fair Value	1,156,256	1,173,722
Total, Unrealized Losses	173,664	194,531
Residential Mortgage-Backed Securities, Non-agency [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	35,839	58,839
Less than 12 months, Unrealized Losses	1,434	2,083
12 months or longer, Fair Value	64,619	42,901
12 months or longer, Unrealized Losses	8,930	7,346
Total, Fair Value	100,458	101,740
Total, Unrealized Losses	10,364	9,429
Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	160,615	396,380
Less than 12 months, Unrealized Losses	3,359	27,469
12 months or longer, Fair Value	373,494	163,226
12 months or longer, Unrealized Losses	53,790	37,754
Total, Fair Value	534,109	559,606
Total, Unrealized Losses	57,149	65,223
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	145,986	425,482
Less than 12 months, Unrealized Losses	2,368	14,134
12 months or longer, Fair Value	751,141	486,129
12 months or longer, Unrealized Losses	23,395	18,068
Total, Fair Value	897,127	911,611
Total, Unrealized Losses	25,763	32,202
Single Issue Trust Preferred Securities [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	3,054	0
Less than 12 months, Unrealized Losses	36	0
12 months or longer, Fair Value	12,784	13,109
12 months or longer, Unrealized Losses	1,478	1,146
Total, Fair Value	15,838	13,109
Total, Unrealized Losses	1,514	1,146
Other corporate securities [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	92,339	195,425
Less than 12 months, Unrealized Losses	5,552	18,064
12 months or longer, Fair Value	334,813	261,170
12 months or longer, Unrealized Losses	31,915	19,867
Total, Fair Value	427,152	456,595
Total, Unrealized Losses	$ 37,467	$ 37,931