Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	$ 3,740,413	$ 3,828,984
Gross Unrealized Gains	6,651	2,105
Gross Unrealized Losses	(444,752)	(501,619)
Fair Value	3,302,312	3,329,470
Held-to-maturity, allowance for credit loss	1,205	1,646	$ 1,165	$ 1,428
Net Carrying Value	3,739,208	3,827,338
U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	26,232	66,911
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(254)	(1,022)
Fair Value	25,978	65,889
Held-to-maturity, allowance for credit loss	0	0
Net Carrying Value	26,232	66,911
U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	305,996	260,392
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(44,441)	(47,680)
Fair Value	261,555	212,712
Held-to-maturity, allowance for credit loss	0	0
Net Carrying Value	305,996	260,392
Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	88,556	99,238
Gross Unrealized Gains	552	305
Gross Unrealized Losses	(4,155)	(3,869)
Fair Value	84,953	95,674
Held-to-maturity, allowance for credit loss	395	252
Net Carrying Value	88,161	98,986
Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	316,914	381,060
Gross Unrealized Gains	40	76
Gross Unrealized Losses	(14,380)	(23,615)
Fair Value	302,574	357,521
Held-to-maturity, allowance for credit loss	49	41
Net Carrying Value	316,865	381,019
Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	405,470	480,298
Gross Unrealized Gains	592	381
Gross Unrealized Losses	(18,535)	(27,484)
Fair Value	387,527	453,195
Held-to-maturity, allowance for credit loss	444	293
Net Carrying Value	405,026	480,005
Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	2,885,303	2,909,106
Gross Unrealized Gains	6,059	1,723
Gross Unrealized Losses	(369,436)	(415,032)
Fair Value	2,521,926	2,495,797
Held-to-maturity, allowance for credit loss	0	0
Net Carrying Value	2,885,303	2,909,106
Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	37,062	37,043
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(6,412)	(5,938)
Fair Value	30,650	31,106
Held-to-maturity, allowance for credit loss	506	888
Net Carrying Value	36,556	36,155
Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	80,350	75,234
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5,674)	(4,463)
Fair Value	74,676	70,771
Held-to-maturity, allowance for credit loss	255	465
Net Carrying Value	$ 80,095	$ 74,769