Securities - Schedule of Unrealized Losses on Investment Securities (Detail) $ in Thousands	Mar. 31, 2023 USD ($) Security	Dec. 31, 2022 USD ($) Security
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 322,669	$ 887,036
Less than 12 months, Unrealized Losses	$ (9,890)	$ (54,828)
Less than 12 months, Number of Securities | Security	198	498
12 months or more, Fair Value	$ 2,116,418	$ 1,619,473
12 months or more, Unrealized Losses	$ (299,297)	$ (291,079)
12 months or more, Number of Securities | Security	519	264
Fair Value, Total	$ 2,439,087	$ 2,506,509
Unrealized Losses, Total	$ (309,187)	$ (345,907)
Number of Securities Total | Security	717	762
U.S. Government Sponsored Entities and Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 28,638	$ 107,011
Less than 12 months, Unrealized Losses	$ (1,020)	$ (8,435)
Less than 12 months, Number of Securities | Security	20	35
12 months or more, Fair Value	$ 194,761	$ 118,779
12 months or more, Unrealized Losses	$ (29,273)	$ (25,015)
12 months or more, Number of Securities | Security	27	13
Fair Value, Total	$ 223,399	$ 225,790
Unrealized Losses, Total	$ (30,293)	$ (33,450)
Number of Securities Total | Security	47	48
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 164,019	$ 514,789
Less than 12 months, Unrealized Losses	$ (7,064)	$ (39,246)
Less than 12 months, Number of Securities | Security	85	294
12 months or more, Fair Value	$ 1,651,930	$ 1,328,906
12 months or more, Unrealized Losses	$ (261,580)	$ (258,741)
12 months or more, Number of Securities | Security	403	202
Fair Value, Total	$ 1,815,949	$ 1,843,695
Unrealized Losses, Total	$ (268,644)	$ (297,987)
Number of Securities Total | Security	488	496
Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 82,142	$ 190,189
Less than 12 months, Unrealized Losses	$ (1,129)	$ (5,106)
Less than 12 months, Number of Securities | Security	17	38
12 months or more, Fair Value	$ 239,347	$ 159,543
12 months or more, Unrealized Losses	$ (5,934)	$ (4,974)
12 months or more, Number of Securities | Security	51	36
Fair Value, Total	$ 321,489	$ 349,732
Unrealized Losses, Total	$ (7,063)	$ (10,080)
Number of Securities Total | Security	68	74
Obligations of State and Political Subdivisions [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 42,991	$ 67,822
Less than 12 months, Unrealized Losses	$ (603)	$ (1,815)
Less than 12 months, Number of Securities | Security	75	128
12 months or more, Fair Value	$ 23,479	$ 7,812
12 months or more, Unrealized Losses	$ (2,411)	$ (2,282)
12 months or more, Number of Securities | Security	33	10
Fair Value, Total	$ 66,470	$ 75,634
Unrealized Losses, Total	$ (3,014)	$ (4,097)
Number of Securities Total | Security	108	138
Corporate Debt Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 4,879	$ 7,225
Less than 12 months, Unrealized Losses	$ (74)	$ (226)
Less than 12 months, Number of Securities | Security	1	3
12 months or more, Fair Value	$ 6,901	$ 4,433
12 months or more, Unrealized Losses	$ (99)	$ (67)
12 months or more, Number of Securities | Security	5	3
Fair Value, Total	$ 11,780	$ 11,658
Unrealized Losses, Total	$ (173)	$ (293)
Number of Securities Total | Security	6	6