Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2024	Dec. 31, 2023
Fair value of securities available for sale:
Due in 1 Year or Less	$ 4,194
Due > 1 Year through 5 Years	6,875
Due > 5 Years through 10 Years	5,330
Due > 10 Years	67,101
Total	83,500	$ 79,117
Amortized cost of securities available for sale
Due in 1 Year or Less	4,204
Due > 1 Year through 5 Years	6,980
Due > 5 Years through 10 Years	5,569
Due > 10 Years	74,018
Total	$ 90,771	88,063
Weighted-average yield for securities available for sale
Due in 1 Year or Less	4.74%
Due > 1 Year through 5 Years	4.07%
Due > 5 Years through 10 Years	3.89%
Due > 10 Years	3.16%
Total	3.35%
U.S. Treasury securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 3,334
Due > 1 Year through 5 Years	1,254
Due > 5 Years through 10 Years	1,444
Due > 10 Years	0
Total	6,032	5,282
Amortized cost of securities available for sale
Total	6,035	5,330
RMBS, Agency
Fair value of securities available for sale:
Due in 1 Year or Less	1
Due > 1 Year through 5 Years	74
Due > 5 Years through 10 Years	1,099
Due > 10 Years	64,477
Total	65,651	62,948
Amortized cost of securities available for sale
Total	72,576	71,294
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	12
Due > 10 Years	644
Total	656	690
Amortized cost of securities available for sale
Total	576	610
Total RMBS
Fair value of securities available for sale:
Due in 1 Year or Less	1
Due > 1 Year through 5 Years	74
Due > 5 Years through 10 Years	1,111
Due > 10 Years	65,121
Total	66,307	63,638
Amortized cost of securities available for sale
Total	$ 73,152	71,904
Weighted-average yield for securities available for sale
Weighted-average expected life	7 years 4 months 24 days
Agency CMBS
Fair value of securities available for sale:
Due in 1 Year or Less	$ 515
Due > 1 Year through 5 Years	2,930
Due > 5 Years through 10 Years	2,758
Due > 10 Years	1,980
Total	8,183	8,323
Amortized cost of securities available for sale
Total	$ 8,613	8,961
Weighted-average yield for securities available for sale
Weighted-average expected life	4 years 10 months 24 days
Other securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 344
Due > 1 Year through 5 Years	2,617
Due > 5 Years through 10 Years	17
Due > 10 Years	0
Total	2,978	1,874
Amortized cost of securities available for sale
Total	$ 2,971	$ 1,868

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

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