Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Debt Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,716,120	$ 1,454,439
Gross Unrealized Gains	17,371	747
Gross Unrealized Losses	(131,231)	(158,610)
Fair Value	2,602,260	1,296,576
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	318,090	313,772
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(22,029)	(25,615)
Fair Value	296,061	288,157
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,634	25,967
Gross Unrealized Gains	24	19
Gross Unrealized Losses	(1,446)	(2,284)
Fair Value	23,212	23,702
Obligations of states and state agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	47,235	48,283
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(504)	(588)
Fair Value	46,731	47,695
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	180,001	170,260
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(24,886)	(26,265)
Fair Value	155,115	143,995
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	227,236	218,543
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(25,390)	(26,853)
Fair Value	201,846	191,690
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,943,569	703,875
Gross Unrealized Gains	17,293	728
Gross Unrealized Losses	(64,994)	(78,031)
Fair Value	1,895,868	626,572
Corporate and other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	202,591	192,282
Gross Unrealized Gains	54	0
Gross Unrealized Losses	(17,372)	(25,827)
Fair Value	$ 185,273	$ 166,455