Investments - Summary of Gross Unrealized Losses and Fair Value of Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	$ 50,294	$ 488,446
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(2,877)	(39,483)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	1,041,202	681,683
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(143,188)	(108,618)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	1,091,496	1,170,129
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(146,065)	(148,101)
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Fair Value	1,367
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Unrealized Loss	(9)
Total temporarily impaired securities, Held-to-maturity securities, Fair Value	1,367
Total temporarily impaired securities, Held-to-maturity securities, Unrealized Loss	(9)
U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value		3,936
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss		(913)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	107,372	102,470
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(15,471)	(15,877)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	107,372	106,406
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(15,471)	(16,790)
U.S. Treasury securities [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	1,403	92,896
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(2)	(6,866)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	233,295	139,262
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(24,755)	(18,666)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	234,698	232,158
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(24,757)	(25,532)
Government-Sponsored Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	17,265	203,416
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(848)	(15,511)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	448,806	295,190
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(59,538)	(46,659)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	466,071	498,606
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(60,386)	(62,170)
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Fair Value	1,094
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Unrealized Loss	(7)
Total temporarily impaired securities, Held-to-maturity securities, Fair Value	1,094
Total temporarily impaired securities, Held-to-maturity securities, Unrealized Loss	(7)
Private Label Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value		43,610
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss		(7,227)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	151,976	116,410
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(27,031)	(20,119)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	151,976	160,020
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(27,031)	(27,346)
Corporate [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	10,765	48,199
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(1,735)	(3,443)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	38,183	4,175
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(5,999)	(825)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	48,948	52,374
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(7,734)	(4,268)
Small Business Administration Loan Pools [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	5,991	7,676
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(4)	(60)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	4,723	4,505
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(730)	(674)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	10,714	12,181
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(734)	(734)
State and Political Subdivisions [Member]
Schedule of Investments [Line Items]
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Fair Value	14,870	88,713
Total temporarily impaired securities, Available-for-sale securities, Less Than 12 Months, Unrealized Loss	(288)	(5,463)
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Fair Value	56,847	19,671
Total temporarily impaired securities, Available-for-sale securities, 12 Months or More, Unrealized Loss	(9,664)	(5,798)
Total temporarily impaired securities, Available-for-sale securities, Fair Value	71,717	108,384
Total temporarily impaired securities, Available-for-sale securities, Unrealized Loss	(9,952)	$ (11,261)
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Fair Value	273
Total temporarily impaired securities, Held-to-maturity securities, Less Than 12 Months, Unrealized Loss	(2)
Total temporarily impaired securities, Held-to-maturity securities, Fair Value	273
Total temporarily impaired securities, Held-to-maturity securities, Unrealized Loss	$ (2)