Securities - Schedule of Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
AFS debt securities:
Amortized Cost	$ 7,072,240	$ 6,879,225
Gross Unrealized Gains	482	498
Gross Unrealized Losses	(771,854)	(844,730)
Fair Value	6,300,868	6,034,993
HTM debt securities:
Amortized Cost	2,993,421	3,001,868
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(490,747)	(546,697)
Fair Value	2,502,674	2,455,171
Total debt securities
Amortized Cost	10,065,661	9,881,093
Gross Unrealized Gains	482	498
Gross Unrealized Losses	(1,262,601)	(1,391,427)
Fair Value	8,803,542	8,490,164
U.S. Treasury securities
AFS debt securities:
Amortized Cost	976,615	676,306
Gross Unrealized Gains	37	0
Gross Unrealized Losses	(59,670)	(70,103)
Fair Value	916,982	606,203
HTM debt securities:
Amortized Cost	525,432	524,081
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(43,821)	(52,612)
Fair Value	481,611	471,469
U.S. government agency and U.S. government-sponsored enterprise debt securities
AFS debt securities:
Amortized Cost	515,639	517,806
Gross Unrealized Gains	0	67
Gross Unrealized Losses	(51,779)	(56,266)
Fair Value	463,860	461,607
HTM debt securities:
Amortized Cost	999,855	998,972
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(193,514)	(209,560)
Fair Value	806,341	789,412
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	564,145	577,392
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(67,030)	(77,123)
Fair Value	497,115	500,269
HTM debt securities:
Amortized Cost	505,492	506,965
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(83,532)	(98,566)
Fair Value	421,960	408,399
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
AFS debt securities:
Amortized Cost	1,997,737	2,011,054
Gross Unrealized Gains	46	41
Gross Unrealized Losses	(225,701)	(248,900)
Fair Value	1,772,082	1,762,195
HTM debt securities:
Amortized Cost	773,135	782,141
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(134,969)	(148,230)
Fair Value	638,166	633,911
Municipal securities
AFS debt securities:
Amortized Cost	305,125	303,884
Gross Unrealized Gains	47	3
Gross Unrealized Losses	(39,157)	(46,788)
Fair Value	266,015	257,099
HTM debt securities:
Amortized Cost	189,507	189,709
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(34,911)	(37,729)
Fair Value	154,596	151,980
Non-agency commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	441,795	447,512
Gross Unrealized Gains	157	213
Gross Unrealized Losses	(45,229)	(49,396)
Fair Value	396,723	398,329
Non-agency residential mortgage-backed securities
AFS debt securities:
Amortized Cost	743,977	762,202
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(105,568)	(112,978)
Fair Value	638,409	649,224
Corporate debt securities
AFS debt securities:
Amortized Cost	663,502	673,502
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(147,249)	(147,228)
Fair Value	516,253	526,274
Foreign government bonds
AFS debt securities:
Amortized Cost	198,517	241,165
Gross Unrealized Gains	195	174
Gross Unrealized Losses	(12,829)	(14,286)
Fair Value	185,883	227,053
Asset-backed securities
AFS debt securities:
Amortized Cost	47,938	51,152
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,631)	(2,076)
Fair Value	46,307	49,076
Collateralized loan obligations (“CLOs”)
AFS debt securities:
Amortized Cost	617,250	617,250
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(16,011)	(19,586)
Fair Value	$ 601,239	$ 597,664