Securities - Scheduled Contractual Maturities of AFS (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Amortized cost
Within One Year	$ 137,562
After One Year through Five Years	908,571
After Five Years through Ten Years	707,680
After Ten Years	7,890,564
Amortized Cost	9,644,377	$ 6,916,491
Fair value
Within One Year	135,806
After One Year through Five Years	850,152
After Five Years through Ten Years	623,808
After Ten Years	7,313,762
Total	$ 8,923,528
Weighted Average Yield
Within One Year	4.89%
After One Year through Five Years	1.50%
After Five Years through Ten Years	3.39%
After Ten Years	4.84%
Total	4.42%
U.S. Treasury securities
Amortized cost
Within One Year	$ 34,929
After One Year through Five Years	641,362
After Five Years through Ten Years	0
After Ten Years	0
Amortized Cost	676,291
Fair value
Within One Year	34,182
After One Year through Five Years	589,575
After Five Years through Ten Years	0
After Ten Years	0
Total	$ 623,757
Weighted Average Yield
Within One Year	1.83%
After One Year through Five Years	1.17%
After Five Years through Ten Years	0.00%
After Ten Years	0.00%
Total	1.21%
U.S. government agency and U.S. government-sponsored enterprise debt securities
Amortized cost
Within One Year	$ 1,238
After One Year through Five Years	44,158
After Five Years through Ten Years	127,831
After Ten Years	136,729
Amortized Cost	309,956
Fair value
Within One Year	1,208
After One Year through Five Years	41,133
After Five Years through Ten Years	107,143
After Ten Years	110,904
Total	$ 260,388
Weighted Average Yield
Within One Year	2.52%
After One Year through Five Years	1.07%
After Five Years through Ten Years	1.59%
After Ten Years	2.33%
Total	1.85%
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities
Amortized cost
Within One Year	$ 3,565
After One Year through Five Years	41,983
After Five Years through Ten Years	126,229
After Ten Years	6,283,304
Amortized Cost	6,455,081
Fair value
Within One Year	3,483
After One Year through Five Years	39,915
After Five Years through Ten Years	116,502
After Ten Years	6,003,765
Total	$ 6,163,665
Weighted Average Yield
Within One Year	2.74%
After One Year through Five Years	2.98%
After Five Years through Ten Years	2.82%
After Ten Years	5.46%
Total	5.39%
Municipal securities
Amortized cost
Within One Year	$ 3,605
After One Year through Five Years	33,531
After Five Years through Ten Years	9,619
After Ten Years	248,682
Amortized Cost	295,437
Fair value
Within One Year	3,543
After One Year through Five Years	31,354
After Five Years through Ten Years	8,793
After Ten Years	212,873
Total	$ 256,563
Weighted Average Yield
Within One Year	2.43%
After One Year through Five Years	2.29%
After Five Years through Ten Years	3.22%
After Ten Years	2.23%
Total	2.27%
Non-agency mortgage-backed securities
Amortized cost
Within One Year	$ 75,391
After One Year through Five Years	20,848
After Five Years through Ten Years	0
After Ten Years	828,788
Amortized Cost	925,027
Fair value
Within One Year	74,622
After One Year through Five Years	20,385
After Five Years through Ten Years	0
After Ten Years	700,248
Total	$ 795,255
Weighted Average Yield
Within One Year	6.89%
After One Year through Five Years	4.00%
After Five Years through Ten Years	0.00%
After Ten Years	2.50%
Total	2.89%
Corporate debt securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	349,501
After Ten Years	304,000
Amortized Cost	653,501
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	297,135
After Ten Years	209,995
Total	$ 507,130
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	3.50%
After Ten Years	1.97%
Total	2.79%
Foreign government bonds
Amortized cost
Within One Year	$ 18,834
After One Year through Five Years	126,689
After Five Years through Ten Years	50,000
After Ten Years	50,000
Amortized Cost	245,523
Fair value
Within One Year	18,768
After One Year through Five Years	127,790
After Five Years through Ten Years	49,782
After Ten Years	37,384
Total	$ 233,724
Weighted Average Yield
Within One Year	3.61%
After One Year through Five Years	2.22%
After Five Years through Ten Years	5.72%
After Ten Years	1.50%
Total	2.89%
Asset-backed securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	39,061
Amortized Cost	39,061
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	38,593
Total	$ 38,593
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	0.00%
After Ten Years	6.06%
Total	6.06%
Collateralized loan obligations (“CLOs”)
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	44,500
After Ten Years	0
Amortized Cost	44,500
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	44,453
After Ten Years	0
Total	$ 44,453
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	6.79%
After Ten Years	0.00%
Total	6.79%