Securities - Schedule of Debt Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
AFS debt securities:
Amortized Cost	$ 13,035,258	$ 11,505,775
Gross Unrealized Gains	34,623	15,273
Gross Unrealized Losses	(580,968)	(674,237)
Fair Value	12,488,913	10,846,811
HTM debt securities:
Amortized Cost	2,892,982	2,917,413
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(455,735)	(529,659)
Fair Value	2,437,247	2,387,754
Total debt securities
Amortized Cost	15,928,240	14,423,188
Gross Unrealized Gains	34,623	15,273
Gross Unrealized Losses	(1,036,703)	(1,203,896)
Fair Value	14,926,160	13,234,565
AFS and HTM, accrued interest	49,000	45,000
Government National Mortgage Association (GNMA)
AFS debt securities:
Amortized Cost	8,900,000	7,300,000
Fair Value	8,900,000	7,200,000
HTM debt securities:
Amortized Cost	82,000	86,000
Fair Value	65,000	68,000
U.S. Treasury securities
AFS debt securities:
Amortized Cost	756,268	676,300
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(25,206)	(38,035)
Fair Value	731,062	638,265
HTM debt securities:
Amortized Cost	537,851	535,080
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(23,084)	(35,222)
Fair Value	514,767	499,858
U.S. government agency and U.S. government-sponsored enterprise debt securities
AFS debt securities:
Amortized Cost	305,615	308,220
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(35,323)	(45,633)
Fair Value	270,292	262,587
HTM debt securities:
Amortized Cost	1,005,738	1,004,479
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(167,516)	(200,259)
Fair Value	838,222	804,220
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	410,247	472,535
Gross Unrealized Gains	937	886
Gross Unrealized Losses	(36,019)	(47,207)
Fair Value	375,165	426,214
HTM debt securities:
Amortized Cost	479,501	486,388
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(76,432)	(91,461)
Fair Value	403,069	394,927
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
AFS debt securities:
Amortized Cost	9,576,977	7,974,768
Gross Unrealized Gains	32,581	12,278
Gross Unrealized Losses	(219,813)	(248,786)
Fair Value	9,389,745	7,738,260
HTM debt securities:
Amortized Cost	683,123	703,833
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(141,511)	(155,626)
Fair Value	541,612	548,207
Municipal securities
AFS debt securities:
Amortized Cost	284,948	287,301
Gross Unrealized Gains	0	38
Gross Unrealized Losses	(45,751)	(37,186)
Fair Value	239,197	250,153
HTM debt securities:
Amortized Cost	186,769	187,633
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(47,192)	(47,091)
Fair Value	139,577	140,542
Non-agency commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	253,719	294,235
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(29,123)	(35,767)
Fair Value	224,596	258,470
Non-agency residential mortgage-backed securities
AFS debt securities:
Amortized Cost	481,295	514,527
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(69,561)	(80,919)
Fair Value	411,734	433,608
Corporate debt securities
AFS debt securities:
Amortized Cost	643,500	653,500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(108,856)	(127,334)
Fair Value	534,644	526,166
Foreign government bonds
AFS debt securities:
Amortized Cost	244,744	244,803
Gross Unrealized Gains	1,105	2,069
Gross Unrealized Losses	(10,506)	(12,992)
Fair Value	235,343	233,880
Asset-backed securities
AFS debt securities:
Amortized Cost	33,445	35,086
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(802)	(371)
Fair Value	32,643	34,715
Collateralized loan obligations (“CLOs”)
AFS debt securities:
Amortized Cost	44,500	44,500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(8)	(7)
Fair Value	$ 44,492	$ 44,493