Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Fair value of securities available for sale:
Due in 1 Year or Less	$ 2,469
Due > 1 Year through 5 Years	7,651
Due > 5 Years through 10 Years	4,656
Due > 10 Years	64,341
Total	79,117	$ 76,919
Amortized cost of securities available for sale
Due in 1 Year or Less	2,491
Due > 1 Year through 5 Years	7,840
Due > 5 Years through 10 Years	5,038
Due > 10 Years	72,694
Total	$ 88,063	87,047
Weighted-average yield for securities available for sale
Due in 1 Year or Less	3.71%
Due > 1 Year through 5 Years	4.04%
Due > 5 Years through 10 Years	3.45%
Due > 10 Years	2.92%
Total	3.08%
U.S. Treasury securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 1,927
Due > 1 Year through 5 Years	3,355
Due > 5 Years through 10 Years	0
Due > 10 Years	0
Total	5,282	5,041
Amortized cost of securities available for sale
Total	5,330	5,129
RMBS, Agency
Fair value of securities available for sale:
Due in 1 Year or Less	1
Due > 1 Year through 5 Years	107
Due > 5 Years through 10 Years	1,123
Due > 10 Years	61,717
Total	62,948	61,852
Amortized cost of securities available for sale
Total	71,294	71,212
RMBS, Non-agency
Fair value of securities available for sale:
Due in 1 Year or Less	0
Due > 1 Year through 5 Years	0
Due > 5 Years through 10 Years	5
Due > 10 Years	685
Total	690	737
Amortized cost of securities available for sale
Total	610	653
Total RMBS
Fair value of securities available for sale:
Due in 1 Year or Less	1
Due > 1 Year through 5 Years	107
Due > 5 Years through 10 Years	1,128
Due > 10 Years	62,402
Total	63,638	62,589
Amortized cost of securities available for sale
Total	$ 71,904	71,865
Weighted-average yield for securities available for sale
Weighted-average expected life	6 years 9 months 18 days
Agency CMBS
Fair value of securities available for sale:
Due in 1 Year or Less	$ 259
Due > 1 Year through 5 Years	2,623
Due > 5 Years through 10 Years	3,502
Due > 10 Years	1,939
Total	8,323	7,870
Amortized cost of securities available for sale
Total	$ 8,961	8,626
Weighted-average yield for securities available for sale
Weighted-average expected life	4 years 7 months 6 days
Other securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 282
Due > 1 Year through 5 Years	1,566
Due > 5 Years through 10 Years	26
Due > 10 Years	0
Total	1,874	1,419
Amortized cost of securities available for sale
Total	$ 1,868	$ 1,427

Available-for-sale Securities, Expected Debt Maturities, Amortized Cost Basis, Rolling Maturity

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