Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Debt Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,415,493	$ 1,437,911
Gross Unrealized Gains	27	111
Gross Unrealized Losses	(228,996)	(176,625)
Fair Value	1,186,524	1,261,397
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	312,348	308,137
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(36,600)	(28,639)
Fair Value	275,748	279,498
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	26,002	29,494
Gross Unrealized Gains	19	47
Gross Unrealized Losses	(3,450)	(2,577)
Fair Value	22,571	26,964
Obligations of states and state agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	49,810	10,899
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,006)	(493)
Fair Value	48,804	10,406
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	170,002	171,586
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(47,334)	(35,181)
Fair Value	122,668	136,405
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	219,812	182,485
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(48,340)	(35,674)
Fair Value	171,472	146,811
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	665,150	719,868
Gross Unrealized Gains	8	64
Gross Unrealized Losses	(111,731)	(90,114)
Fair Value	553,427	629,818
Corporate and other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	192,181	197,927
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(28,875)	(19,621)
Fair Value	$ 163,306	$ 178,306