Securities - Scheduled Contractual Maturities of AFS Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Amortized cost
Within One Year	$ 181,986
After One Year through Five Years	826,506
After Five Years through Ten Years	785,584
After Ten Years	9,711,699
Amortized Cost	11,505,775	$ 6,916,491
Fair value
Within One Year	180,152
After One Year through Five Years	785,567
After Five Years through Ten Years	703,341
After Ten Years	9,177,751
Total	$ 10,846,811
Weighted-Average Yield
Within One Year	2.62%
After One Year through Five Years	1.40%
After Five Years through Ten Years	3.26%
After Ten Years	4.70%
Total	4.33%
U.S. Treasury securities
Amortized cost
Within One Year	$ 84,143
After One Year through Five Years	592,157
After Five Years through Ten Years	0
After Ten Years	0
Amortized Cost	676,300	1,112,587
Fair value
Within One Year	83,367
After One Year through Five Years	554,898
After Five Years through Ten Years	0
After Ten Years	0
Total	$ 638,265
Weighted-Average Yield
Within One Year	2.23%
After One Year through Five Years	1.06%
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	$ 17,972
After One Year through Five Years	27,030
After Five Years through Ten Years	201,546
After Ten Years	61,672
Amortized Cost	308,220	412,086
Fair value
Within One Year	17,595
After One Year through Five Years	25,492
After Five Years through Ten Years	169,448
After Ten Years	50,052
Total	$ 262,587
Weighted-Average Yield
Within One Year	1.06%
After One Year through Five Years	1.13%
After Five Years through Ten Years	2.01%
After Ten Years	2.00%
Total	1.87%
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities
Amortized cost
Within One Year	$ 8,037
After One Year through Five Years	54,584
After Five Years through Ten Years	125,704
After Ten Years	8,258,978
Amortized Cost	8,447,303
Fair value
Within One Year	7,990
After One Year through Five Years	51,845
After Five Years through Ten Years	114,109
After Ten Years	7,990,530
Total	$ 8,164,474
Weighted-Average Yield
Within One Year	3.24%
After One Year through Five Years	2.89%
After Five Years through Ten Years	2.79%
After Ten Years	5.13%
Total	5.07%
Municipal securities
Amortized cost
Within One Year	$ 5,657
After One Year through Five Years	26,502
After Five Years through Ten Years	8,114
After Ten Years	247,028
Amortized Cost	287,301	297,283
Fair value
Within One Year	5,558
After One Year through Five Years	25,160
After Five Years through Ten Years	7,394
After Ten Years	212,041
Total	$ 250,153
Weighted-Average Yield
Within One Year	2.25%
After One Year through Five Years	2.14%
After Five Years through Ten Years	3.38%
After Ten Years	2.23%
Total	2.25%
Non-agency mortgage-backed securities
Amortized cost
Within One Year	$ 39,936
After One Year through Five Years	7,671
After Five Years through Ten Years	6,220
After Ten Years	754,935
Amortized Cost	808,762
Fair value
Within One Year	39,337
After One Year through Five Years	7,605
After Five Years through Ten Years	6,207
After Ten Years	638,929
Total	$ 692,078
Weighted-Average Yield
Within One Year	3.67%
After One Year through Five Years	2.95%
After Five Years through Ten Years	5.53%
After Ten Years	2.40%
Total	2.49%
Corporate debt securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	349,500
After Ten Years	304,000
Amortized Cost	653,500	653,501
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	311,947
After Ten Years	214,219
Total	$ 526,166
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	$ 26,241
After One Year through Five Years	118,562
After Five Years through Ten Years	50,000
After Ten Years	50,000
Amortized Cost	244,803	239,333
Fair value
Within One Year	26,305
After One Year through Five Years	120,567
After Five Years through Ten Years	49,743
After Ten Years	37,265
Total	$ 233,880
Weighted-Average Yield
Within One Year	3.24%
After One Year through Five Years	2.22%
After Five Years through Ten Years	5.01%
After Ten Years	1.50%
Total	2.75%
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	35,086
Amortized Cost	35,086	43,234
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	34,715
Total	$ 34,715
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	5.37%
Total	5.37%
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	$ 617,250
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	44,493
After Ten Years	0
Total	$ 44,493
Weighted-Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	6.08%
After Ten Years	0.00%
Total	6.08%