Securities - Amortized Cost and Fair Value of Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,069,695	$ 1,104,105
Gross Unrealized Gains	0	261
Gross Unrealized Losses	(115,428)	(102,582)
Fair Value	954,267	1,001,784
Interest receivable	3,400	3,700
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	144,575	145,416
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(14,538)	(13,721)
Fair Value	130,037	131,695
Obligations of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	43,377	43,479
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,328)	(1,668)
Fair Value	42,049	41,811
Collateralized mortgage obligations of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	493,359	482,039
Gross Unrealized Gains	0	203
Gross Unrealized Losses	(63,381)	(53,835)
Fair Value	429,978	428,407
Residential mortgage-backed securities of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,802	49,418
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(8,916)	(7,834)
Fair Value	36,886	41,587
Commercial mortgage-backed securities of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	312,191	352,465
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(26,084)	(25,152)
Fair Value	286,107	327,313
Corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	500
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	30,391	30,788
Gross Unrealized Gains	0	55
Gross Unrealized Losses	(1,181)	(372)
Fair Value	$ 29,210	$ 30,471