Investment Securities - Schedule of Gross Unrealized Losses and Fair Value by Length of Time that the Individual Available-For-Sale Securities Have Been in a Continuous Unrealized Loss (Details) $ in Thousands	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	251	260
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 485,502	$ 495,164
Investment securities available-for-sale, Less than 12 months, unrealized losses	(59,495)	(58,439)
Investment securities available-for-sale, 12 months or greater, estimated fair value	985,946	1,093,919
Investment securities available-for-sale, 12 months or greater, unrealized losses	(165,777)	(146,839)
Investment securities available-for-sale, Estimated fair value	1,471,448	1,589,083
Investment securities available-for-sale, Unrealized losses	$ (225,272)	$ (205,278)
Investment securities held-to-maturity, Number of securities | security	230	232
Investment securities held-to-maturity, Less than 12 months, estimated fair value	$ 29,443	$ 23,881
Investment securities held-to-maturity, Less than 12 months, unrealized losses	(3,596)	(3,228)
Investment securities held-to-maturity, 12 months or greater, estimated fair value	826,433	932,753
Investment securities held-to-maturity, 12 months or greater, unrealized losses	(161,017)	(122,205)
Investment securities held-to-maturity, Estimated Fair Value	855,876	956,634
Investment securities held-to-maturity, Unrealized losses	$ (164,613)	$ (125,433)
U.S. treasury bonds
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	2	2
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 0	$ 0
Investment securities available-for-sale, Less than 12 months, unrealized losses	0	0
Investment securities available-for-sale, 12 months or greater, estimated fair value	47,050	46,327
Investment securities available-for-sale, 12 months or greater, unrealized losses	(2,818)	(3,466)
Investment securities available-for-sale, Estimated fair value	47,050	46,327
Investment securities available-for-sale, Unrealized losses	$ (2,818)	$ (3,466)
U. S. agency securities
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	78	85
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 485,494	$ 490,699
Investment securities available-for-sale, Less than 12 months, unrealized losses	(59,495)	(58,437)
Investment securities available-for-sale, 12 months or greater, estimated fair value	167,358	179,029
Investment securities available-for-sale, 12 months or greater, unrealized losses	(20,307)	(19,612)
Investment securities available-for-sale, Estimated fair value	652,852	669,728
Investment securities available-for-sale, Unrealized losses	$ (79,802)	$ (78,049)
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	156	157
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 8	$ 3,994
Investment securities available-for-sale, Less than 12 months, unrealized losses	0	0
Investment securities available-for-sale, 12 months or greater, estimated fair value	714,068	808,697
Investment securities available-for-sale, 12 months or greater, unrealized losses	(134,407)	(117,072)
Investment securities available-for-sale, Estimated fair value	714,076	812,691
Investment securities available-for-sale, Unrealized losses	$ (134,407)	$ (117,072)
Investment securities held-to-maturity, Number of securities | security	143	143
Investment securities held-to-maturity, Less than 12 months, estimated fair value	$ 0	$ 0
Investment securities held-to-maturity, Less than 12 months, unrealized losses	0	0
Investment securities held-to-maturity, 12 months or greater, estimated fair value	576,058	652,667
Investment securities held-to-maturity, 12 months or greater, unrealized losses	(109,590)	(88,390)
Investment securities held-to-maturity, Estimated Fair Value	576,058	652,667
Investment securities held-to-maturity, Unrealized losses	$ (109,590)	$ (88,390)
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	13	14
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 0	$ 471
Investment securities available-for-sale, Less than 12 months, unrealized losses	0	(2)
Investment securities available-for-sale, 12 months or greater, estimated fair value	48,004	49,742
Investment securities available-for-sale, 12 months or greater, unrealized losses	(6,900)	(5,856)
Investment securities available-for-sale, Estimated fair value	48,004	50,213
Investment securities available-for-sale, Unrealized losses	$ (6,900)	$ (5,858)
Investment securities held-to-maturity, Number of securities | security	16	16
Investment securities held-to-maturity, Less than 12 months, estimated fair value	$ 0	$ 0
Investment securities held-to-maturity, Less than 12 months, unrealized losses	0	0
Investment securities held-to-maturity, 12 months or greater, estimated fair value	74,532	80,564
Investment securities held-to-maturity, 12 months or greater, unrealized losses	(16,805)	(11,993)
Investment securities held-to-maturity, Estimated Fair Value	74,532	80,564
Investment securities held-to-maturity, Unrealized losses	$ (16,805)	$ (11,993)
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	1	1
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 0	$ 0
Investment securities available-for-sale, Less than 12 months, unrealized losses	0	0
Investment securities available-for-sale, 12 months or greater, estimated fair value	7,802	8,299
Investment securities available-for-sale, 12 months or greater, unrealized losses	(1,026)	(658)
Investment securities available-for-sale, Estimated fair value	7,802	8,299
Investment securities available-for-sale, Unrealized losses	$ (1,026)	$ (658)
Investment securities held-to-maturity, Number of securities | security	41	43
Investment securities held-to-maturity, Less than 12 months, estimated fair value	$ 5,866	$ 3,110
Investment securities held-to-maturity, Less than 12 months, unrealized losses	(162)	(45)
Investment securities held-to-maturity, 12 months or greater, estimated fair value	97,879	113,071
Investment securities held-to-maturity, 12 months or greater, unrealized losses	(19,371)	(12,047)
Investment securities held-to-maturity, Estimated Fair Value	103,745	116,181
Investment securities held-to-maturity, Unrealized losses	$ (19,533)	$ (12,092)
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Investment securities available-for-sale, Number of securities | security	1	1
Investment securities available-for-sale, Less than 12 months, estimated fair value	$ 0	$ 0
Investment securities available-for-sale, Less than 12 months, unrealized losses	0	0
Investment securities available-for-sale, 12 months or greater, estimated fair value	1,664	1,825
Investment securities available-for-sale, 12 months or greater, unrealized losses	(319)	(175)
Investment securities available-for-sale, Estimated fair value	1,664	1,825
Investment securities available-for-sale, Unrealized losses	$ (319)	$ (175)
Investment securities held-to-maturity, Number of securities | security	30	30
Investment securities held-to-maturity, Less than 12 months, estimated fair value	$ 23,577	$ 20,771
Investment securities held-to-maturity, Less than 12 months, unrealized losses	(3,434)	(3,183)
Investment securities held-to-maturity, 12 months or greater, estimated fair value	77,964	86,451
Investment securities held-to-maturity, 12 months or greater, unrealized losses	(15,251)	(9,775)
Investment securities held-to-maturity, Estimated Fair Value	101,541	107,222
Investment securities held-to-maturity, Unrealized losses	$ (18,685)	$ (12,958)