Securities - Schedule of Unrealized Losses on Investment Securities (Detail) $ in Thousands	Dec. 31, 2023 USD ($) Security	Dec. 31, 2022 USD ($) Security
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 20,407	$ 887,036
Less than 12 months, Unrealized Losses	$ (136)	$ (54,828)
Less than 12 months, Number of Securities | Security	24	498
12 months or more, Fair Value	$ 2,141,624	$ 1,619,473
12 months or more, Unrealized Losses	$ (306,948)	$ (291,079)
12 months or more, Number of Securities | Security	654	264
Fair Value, Total	$ 2,162,031	$ 2,506,509
Unrealized Losses, Total	$ (307,084)	$ (345,907)
Number of Securities Total | Security	678	762
U.S. Government Sponsored Entities and Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 18	$ 107,011
Less than 12 months, Unrealized Losses	$ (1)	$ (8,435)
Less than 12 months, Number of Securities | Security	1	35
12 months or more, Fair Value	$ 208,348	$ 118,779
12 months or more, Unrealized Losses	$ (30,309)	$ (25,015)
12 months or more, Number of Securities | Security	45	13
Fair Value, Total	$ 208,366	$ 225,790
Unrealized Losses, Total	$ (30,310)	$ (33,450)
Number of Securities Total | Security	46	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		$ 514,789
Less than 12 months, Unrealized Losses		$ (39,246)
Less than 12 months, Number of Securities | Security		294
12 months or more, Fair Value	$ 1,625,144	$ 1,328,906
12 months or more, Unrealized Losses	$ (267,874)	$ (258,741)
12 months or more, Number of Securities | Security	467	202
Fair Value, Total	$ 1,625,144	$ 1,843,695
Unrealized Losses, Total	$ (267,874)	$ (297,987)
Number of Securities Total | Security	467	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	$ 5,520	$ 190,189
Less than 12 months, Unrealized Losses	$ (31)	$ (5,106)
Less than 12 months, Number of Securities | Security	1	38
12 months or more, Fair Value	$ 251,765	$ 159,543
12 months or more, Unrealized Losses	$ (5,893)	$ (4,974)
12 months or more, Number of Securities | Security	60	36
Fair Value, Total	$ 257,285	$ 349,732
Unrealized Losses, Total	$ (5,924)	$ (10,080)
Number of Securities Total | Security	61	74
Obligations of State and Political Subdivisions [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 10,387	$ 67,822
Less than 12 months, Unrealized Losses	$ (86)	$ (1,815)
Less than 12 months, Number of Securities | Security	19	128
12 months or more, Fair Value	$ 49,002	$ 7,812
12 months or more, Unrealized Losses	$ (2,775)	$ (2,282)
12 months or more, Number of Securities | Security	79	10
Fair Value, Total	$ 59,389	$ 75,634
Unrealized Losses, Total	$ (2,861)	$ (4,097)
Number of Securities Total | Security	98	138
Corporate Debt Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 4,482	$ 7,225
Less than 12 months, Unrealized Losses	$ (18)	$ (226)
Less than 12 months, Number of Securities | Security	3	3
12 months or more, Fair Value	$ 7,365	$ 4,433
12 months or more, Unrealized Losses	$ (97)	$ (67)
12 months or more, Number of Securities | Security	3	3
Fair Value, Total	$ 11,847	$ 11,658
Unrealized Losses, Total	$ (115)	$ (293)
Number of Securities Total | Security	6	6