Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 3,719,977	$ 2,668,697
Gross Unrealized Gains	2,301	25,980
Gross Unrealized Losses	(328,563)	(34,072)
Fair Value	3,393,715	2,660,605
U.S. Treasury securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	67,238	67,558
Gross Unrealized Gains	573	4,103
Gross Unrealized Losses	(29)	0
Fair Value	67,782	71,661
U.S. government agency securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	259,711	6,265
Gross Unrealized Gains	138	113
Gross Unrealized Losses	(16,495)	0
Fair Value	243,354	6,378
Obligations of states and state agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	102,677	141,015
Gross Unrealized Gains	222	3,065
Gross Unrealized Losses	(2,468)	(312)
Fair Value	100,431	143,768
Municipal bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	402,090	196,947
Gross Unrealized Gains	520	3,536
Gross Unrealized Losses	(16,707)	(87)
Fair Value	385,903	200,396
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	504,767	337,962
Gross Unrealized Gains	742	6,601
Gross Unrealized Losses	(19,175)	(399)
Fair Value	486,334	344,164
Residential mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,775,928	2,166,142
Gross Unrealized Gains	814	14,599
Gross Unrealized Losses	(284,005)	(28,440)
Fair Value	2,492,737	2,152,301
Trust preferred securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	37,033	37,020
Gross Unrealized Gains	3	5
Gross Unrealized Losses	(5,583)	(5,109)
Fair Value	31,453	31,916
Corporate and other debt securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	75,300	53,750
Gross Unrealized Gains	31	559
Gross Unrealized Losses	(3,276)	(124)
Fair Value	$ 72,055	$ 54,185