Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2025	Dec. 31, 2024
Fair value of securities available for sale:
Due in 1 Year or Less	$ 3,758
Due > 1 Year through 5 Years	9,009
Due > 5 Years through 10 Years	7,458
Due > 10 Years	69,508
Total	89,733	$ 83,013
Amortized cost of securities available for sale
Due in 1 Year or Less	3,761
Due > 1 Year through 5 Years	9,071
Due > 5 Years through 10 Years	7,641
Due > 10 Years	76,466
Total	$ 96,939	92,995
Weighted-average yield for securities available for sale
Due in 1 Year or Less	4.24%
Due > 1 Year through 5 Years	3.77%
Due > 5 Years through 10 Years	4.09%
Due > 10 Years	3.93%
Total	3.94%
U.S. Treasury securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 2,447
Due > 1 Year through 5 Years	2,390
Due > 5 Years through 10 Years	3,800
Due > 10 Years	0
Total	8,637	6,110
Amortized cost of securities available for sale
Total	8,613	6,114
RMBS, Agency
Fair value of securities available for sale:
Due in 1 Year or Less	4
Due > 1 Year through 5 Years	123
Due > 5 Years through 10 Years	1,135
Due > 10 Years	67,035
Total	68,297	64,707
Amortized cost of securities available for sale
Total	75,246	74,177
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	31
Due > 10 Years	571
Total	602	621
Amortized cost of securities available for sale
Total	536	567
Total RMBS
Fair value of securities available for sale:
Due in 1 Year or Less	4
Due > 1 Year through 5 Years	123
Due > 5 Years through 10 Years	1,166
Due > 10 Years	67,606
Total	68,899	65,328
Amortized cost of securities available for sale
Total	$ 75,782	74,744
Weighted-average yield for securities available for sale
Weighted-average expected life	8 years
Agency CMBS
Fair value of securities available for sale:
Due in 1 Year or Less	$ 1,156
Due > 1 Year through 5 Years	2,957
Due > 5 Years through 10 Years	2,492
Due > 10 Years	1,835
Total	8,440	7,825
Amortized cost of securities available for sale
Total	$ 8,795	8,389
Weighted-average yield for securities available for sale
Weighted-average expected life	4 years 3 months 18 days
Other securities
Fair value of securities available for sale:
Due in 1 Year or Less	$ 151
Due > 1 Year through 5 Years	3,539
Due > 5 Years through 10 Years	0
Due > 10 Years	67
Total	3,757	3,750
Amortized cost of securities available for sale
Total	$ 3,749	$ 3,748

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

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