Securities - Schedule of Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
AFS debt securities:
Amortized Cost	$ 6,771,354	$ 10,087,179
Gross Unrealized Gains	759	51,025
Gross Unrealized Losses	(866,023)	(172,851)
Fair Value	5,906,090	9,965,353
HTM debt securities:
Amortized Cost	3,012,667	0
Gross Unrealized Gains	0
Gross Unrealized Losses	(553,532)
Fair Value	2,459,135
Total debt securities
Amortized Cost	9,784,021
Gross Unrealized Gains	759
Gross Unrealized Losses	(1,419,555)
Fair Value	8,365,225
U.S. Treasury securities
AFS debt securities:
Amortized Cost	676,312	1,049,238
Gross Unrealized Gains	0	130
Gross Unrealized Losses	(75,635)	(16,687)
Fair Value	600,677	1,032,681
HTM debt securities:
Amortized Cost	522,713
Gross Unrealized Gains	0
Gross Unrealized Losses	(56,628)
Fair Value	466,085
U.S. government agency and U.S. government-sponsored enterprise debt securities
AFS debt securities:
Amortized Cost	319,070	1,333,984
Gross Unrealized Gains	0	2,697
Gross Unrealized Losses	(58,646)	(34,710)
Fair Value	260,424	1,301,971
HTM debt securities:
Amortized Cost	998,233
Gross Unrealized Gains	0
Gross Unrealized Losses	(215,616)
Fair Value	782,617
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	595,342	1,242,043
Gross Unrealized Gains	0	15,791
Gross Unrealized Losses	(73,457)	(28,854)
Fair Value	521,885	1,228,980
HTM debt securities:
Amortized Cost	509,139
Gross Unrealized Gains	0
Gross Unrealized Losses	(92,507)
Fair Value	416,632
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
AFS debt securities:
Amortized Cost	2,043,791	2,968,789
Gross Unrealized Gains	58	8,629
Gross Unrealized Losses	(250,420)	(49,135)
Fair Value	1,793,429	2,928,283
HTM debt securities:
Amortized Cost	792,685
Gross Unrealized Gains	0
Gross Unrealized Losses	(142,978)
Fair Value	649,707
Municipal securities
AFS debt securities:
Amortized Cost	307,084	519,381
Gross Unrealized Gains	0	10,065
Gross Unrealized Losses	(57,582)	(6,288)
Fair Value	249,502	523,158
HTM debt securities:
Amortized Cost	189,897
Gross Unrealized Gains	0
Gross Unrealized Losses	(45,803)
Fair Value	144,094
Non-agency commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	448,790	498,920
Gross Unrealized Gains	173	3,000
Gross Unrealized Losses	(50,988)	(5,477)
Fair Value	397,975	496,443
Non-agency residential mortgage-backed securities
AFS debt securities:
Amortized Cost	784,700	889,937
Gross Unrealized Gains	0	971
Gross Unrealized Losses	(113,162)	(8,977)
Fair Value	671,538	881,931
Corporate debt securities
AFS debt securities:
Amortized Cost	673,502	657,516
Gross Unrealized Gains	0	8,738
Gross Unrealized Losses	(143,937)	(16,589)
Fair Value	529,565	649,665
Foreign government bonds
AFS debt securities:
Amortized Cost	238,720	260,447
Gross Unrealized Gains	528	767
Gross Unrealized Losses	(13,438)	(3,481)
Fair Value	225,810	257,733
Asset-backed securities
AFS debt securities:
Amortized Cost	66,793	74,674
Gross Unrealized Gains	0	185
Gross Unrealized Losses	(1,923)	(301)
Fair Value	64,870	74,558
Collateralized loan obligations (“CLOs”)
AFS debt securities:
Amortized Cost	617,250	592,250
Gross Unrealized Gains	0	52
Gross Unrealized Losses	(26,835)	(2,352)
Fair Value	$ 590,415	$ 589,950