Securities - Scheduled Contractual Maturities of ATM and HTM Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Amortized cost
Within One Year	$ 303,496
After One Year through Five Years	958,127
After Five Years through Ten Years	800,818
After Ten Years	4,816,784
Amortized Cost	6,879,225	$ 10,087,179
Fair value
Within One Year	302,412
After One Year through Five Years	886,140
After Five Years through Ten Years	707,539
After Ten Years	4,138,902
Total	$ 6,034,993
Weighted-Average Yield
Within One Year	3.66%
After One Year through Five Years	2.18%
After Five Years through Ten Years	2.76%
After Ten Years	3.16%
Total	3.00%
Amortized cost
Within One Year	$ 0
After One Year through Five Years	404,252
After Five Years through Ten Years	471,892
After Ten Years	2,125,724
Total	3,001,868
Fair value
Within One Year	0
After One Year through Five Years	364,360
After Five Years through Ten Years	404,155
After Ten Years	1,686,656
Total	$ 2,455,171
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	1.01%
After Five Years through Ten Years	1.67%
After Ten Years	1.78%
Total	1.66%
U.S. Treasury securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	576,585
After Five Years through Ten Years	99,721
After Ten Years	0
Amortized Cost	676,306	1,049,238
Fair value
Within One Year	0
After One Year through Five Years	521,174
After Five Years through Ten Years	85,029
After Ten Years	0
Total	$ 606,203
Weighted-Average Yield
Within One Year	0.00%
After One Year through Five Years	1.28%
After Five Years through Ten Years	0.74%
After Ten Years	0.00%
Total	1.20%
Amortized cost
Within One Year	$ 0
After One Year through Five Years	404,252
After Five Years through Ten Years	119,829
After Ten Years	0
Total	524,081
Fair value
Within One Year	0
After One Year through Five Years	364,360
After Five Years through Ten Years	107,109
After Ten Years	0
Total	$ 471,469
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	1.01%
After Five Years through Ten Years	1.18%
After Ten Years	0.00%
Total	1.05%
U.S. government agency and U.S. government-sponsored enterprise debt securities
Amortized cost
Within One Year	$ 100,000
After One Year through Five Years	149,772
After Five Years through Ten Years	100,000
After Ten Years	168,034
Amortized Cost	517,806	1,333,984
Fair value
Within One Year	99,939
After One Year through Five Years	144,796
After Five Years through Ten Years	81,973
After Ten Years	134,899
Total	$ 461,607
Weighted-Average Yield
Within One Year	4.97%
After One Year through Five Years	3.71%
After Five Years through Ten Years	1.26%
After Ten Years	2.10%
Total	2.96%
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	255,967
After Ten Years	743,005
Total	998,972
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	216,340
After Ten Years	573,072
Total	$ 789,412
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	1.94%
After Ten Years	1.88%
Total	1.90%
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	31,165
After Five Years through Ten Years	161,960
After Ten Years	2,395,321
Amortized Cost	2,588,446
Fair value
Within One Year	0
After One Year through Five Years	29,643
After Five Years through Ten Years	146,737
After Ten Years	2,086,084
Total	$ 2,262,464
Weighted-Average Yield
Within One Year	0.00%
After One Year through Five Years	3.20%
After Five Years through Ten Years	2.69%
After Ten Years	3.22%
Total	3.19%
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	96,096
After Ten Years	1,193,010
Total	1,289,106
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	80,706
After Ten Years	961,604
Total	$ 1,042,310
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	1.56%
After Ten Years	1.68%
Total	1.67%
Municipal securities:
Amortized cost
Within One Year	$ 2,307
After One Year through Five Years	34,865
After Five Years through Ten Years	6,847
After Ten Years	259,865
Amortized Cost	303,884	519,381
Fair value
Within One Year	2,283
After One Year through Five Years	32,160
After Five Years through Ten Years	5,780
After Ten Years	216,876
Total	$ 257,099
Weighted-Average Yield
Within One Year	2.21%
After One Year through Five Years	2.40%
After Five Years through Ten Years	1.85%
After Ten Years	2.25%
Total	2.26%
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	189,709
Total	189,709
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	151,980
Total	$ 151,980
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	1.98%
Total	1.98%
Non-agency mortgage-backed securities
Amortized cost
Within One Year	$ 57,190
After One Year through Five Years	158,574
After Five Years through Ten Years	22,788
After Ten Years	971,162
Amortized Cost	1,209,714
Fair value
Within One Year	56,222
After One Year through Five Years	151,239
After Five Years through Ten Years	22,000
After Ten Years	818,092
Total	$ 1,047,553
Weighted-Average Yield
Within One Year	4.93%
After One Year through Five Years	3.78%
After Five Years through Ten Years	0.84%
After Ten Years	2.45%
Total	2.72%
Corporate debt securities
Amortized cost
Within One Year	$ 10,000
After One Year through Five Years	0
After Five Years through Ten Years	334,502
After Ten Years	329,000
Amortized Cost	673,502	657,516
Fair value
Within One Year	9,856
After One Year through Five Years	0
After Five Years through Ten Years	292,049
After Ten Years	224,369
Total	$ 526,274
Weighted-Average Yield
Within One Year	3.77%
After One Year through Five Years	0.00%
After Five Years through Ten Years	3.59%
After Ten Years	1.98%
Total	2.81%
Foreign government bonds
Amortized cost
Within One Year	$ 133,999
After One Year through Five Years	7,166
After Five Years through Ten Years	50,000
After Ten Years	50,000
Amortized Cost	241,165	260,447
Fair value
Within One Year	134,112
After One Year through Five Years	7,128
After Five Years through Ten Years	49,670
After Ten Years	36,143
Total	$ 227,053
Weighted-Average Yield
Within One Year	2.15%
After One Year through Five Years	2.24%
After Five Years through Ten Years	4.18%
After Ten Years	1.50%
Total	2.44%
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	51,152
Amortized Cost	51,152	74,674
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	49,076
Total	$ 49,076
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	5.16%
Total	5.16%
Collateralized loan obligations (“CLOs”)
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	25,000
After Ten Years	592,250
Amortized Cost	617,250	$ 592,250
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	24,301
After Ten Years	573,363
Total	$ 597,664
Weighted-Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	5.23%
After Ten Years	5.40%
Total	5.40%