Securities - Schedule of Unrealized Losses on Investment Securities (Detail) $ in Thousands	Dec. 31, 2024 USD ($) Security	Dec. 31, 2023 USD ($) Security
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 223,438	$ 20,407
Less than 12 months, Unrealized Losses	$ (1,966)	$ (136)
Less than 12 months, Number of Securities | Security	47	24
12 months or more, Fair Value	$ 1,850,875	$ 2,141,624
12 months or more, Unrealized Losses	$ (293,453)	$ (306,948)
12 months or more, Number of Securities | Security	626	654
Fair Value, Total	$ 2,074,313	$ 2,162,031
Unrealized Losses, Total	$ (295,419)	$ (307,084)
Number of Securities Total | Security	673	678
US Treasury Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 48,846
Less than 12 months, Unrealized Losses	$ (63)
Less than 12 months, Number of Securities | Security	2
Fair Value, Total	$ 48,846
Unrealized Losses, Total	$ (63)
Number of Securities Total | Security	2
U.S. Government Sponsored Entities and Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value		$ 18
Less than 12 months, Unrealized Losses		$ (1)
Less than 12 months, Number of Securities | Security		1
12 months or more, Fair Value	$ 194,242	$ 208,348
12 months or more, Unrealized Losses	$ (30,702)	$ (30,309)
12 months or more, Number of Securities | Security	43	45
Fair Value, Total	$ 194,242	$ 208,366
Unrealized Losses, Total	$ (30,702)	$ (30,310)
Number of Securities Total | Security	43	46
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	$ 149,466
Less than 12 months, Unrealized Losses	$ (1,742)
Less than 12 months, Number of Securities | Security	32
12 months or more, Fair Value	$ 1,408,115	$ 1,625,144
12 months or more, Unrealized Losses	$ (255,346)	$ (267,874)
12 months or more, Number of Securities | Security	447	467
Fair Value, Total	$ 1,557,581	$ 1,625,144
Unrealized Losses, Total	$ (257,088)	$ (267,874)
Number of Securities Total | Security	479	467
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	$ 9,919	$ 5,520
Less than 12 months, Unrealized Losses	$ (7)	$ (31)
Less than 12 months, Number of Securities | Security	1	1
12 months or more, Fair Value	$ 193,085	$ 251,765
12 months or more, Unrealized Losses	$ (4,135)	$ (5,893)
12 months or more, Number of Securities | Security	50	60
Fair Value, Total	$ 203,004	$ 257,285
Unrealized Losses, Total	$ (4,142)	$ (5,924)
Number of Securities Total | Security	51	61
Obligations of State and Political Subdivisions [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 10,728	$ 10,387
Less than 12 months, Unrealized Losses	$ (133)	$ (86)
Less than 12 months, Number of Securities | Security	8	19
12 months or more, Fair Value	$ 48,038	$ 49,002
12 months or more, Unrealized Losses	$ (3,191)	$ (2,775)
12 months or more, Number of Securities | Security	84	79
Fair Value, Total	$ 58,766	$ 59,389
Unrealized Losses, Total	$ (3,324)	$ (2,861)
Number of Securities Total | Security	92	98
Corporate Debt Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$ 4,479	$ 4,482
Less than 12 months, Unrealized Losses	$ (21)	$ (18)
Less than 12 months, Number of Securities | Security	4	3
12 months or more, Fair Value	$ 7,395	$ 7,365
12 months or more, Unrealized Losses	$ (79)	$ (97)
12 months or more, Number of Securities | Security	2	3
Fair Value, Total	$ 11,874	$ 11,847
Unrealized Losses, Total	$ (100)	$ (115)
Number of Securities Total | Security	6	6