Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2023	Dec. 31, 2022
Securities available for sale
Due in 1 year or less	$ 2,153
Due after 1 year through 5 years	7,689
Due after 5 years through 10 years	4,435
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	60,560
Securities available for sale	74,837	$ 76,919
Amortized cost of securities available for sale
Due in 1 year or less	2,175
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost	7,961
Due after 5 years through 10 years	4,995
Due > 10 Years	72,519
Amortized Cost	$ 87,650	87,047
Weighted average yield for securities available for sale
Due in 1 Year or Less	3.58%
Due > 1 Year through 5 Years	3.83%
Due > 5 Years through 10 Years	3.28%
Due > 10 Years	2.83%
Total weighted average yield	2.96%
U.S. Treasury securities
Securities available for sale
Due in 1 year or less	$ 1,525
Due after 1 year through 5 years	3,680
Due after 5 years through 10 years	0
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	0
Securities available for sale	5,205	5,041
Amortized cost of securities available for sale
Amortized Cost	5,279	5,129
RMBS, Agency
Securities available for sale
Due in 1 year or less	1
Due after 1 year through 5 years	68
Due after 5 years through 10 years	1,175
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	57,948
Securities available for sale	59,192	61,852
Amortized cost of securities available for sale
Amortized Cost	71,122	71,212
RMBS, Non-agency
Securities available for sale
Due in 1 year or less	0
Due after 1 year through 5 years	0
Due after 5 years through 10 years	3
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	687
Securities available for sale	690	737
Amortized cost of securities available for sale
Amortized Cost	620	653
RMBS
Securities available for sale
Due in 1 year or less	1
Due after 1 year through 5 years	68
Due after 5 years through 10 years	1,178
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	58,635
Securities available for sale	59,882	62,589
Amortized cost of securities available for sale
Amortized Cost	$ 71,742	71,865
Weighted average yield for securities available for sale
Weighted-average expected life	7 years
CMBS, Agency
Securities available for sale
Due in 1 year or less	$ 115
Due after 1 year through 5 years	2,571
Due after 5 years through 10 years	3,228
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	1,925
Securities available for sale	7,839	7,870
Amortized cost of securities available for sale
Amortized Cost	$ 8,718	8,626
Weighted average yield for securities available for sale
Weighted-average expected life	4 years 7 months 6 days
Other securities
Securities available for sale
Due in 1 year or less	$ 512
Due after 1 year through 5 years	1,370
Due after 5 years through 10 years	29
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	0
Securities available for sale	1,911	1,419
Amortized cost of securities available for sale
Amortized Cost	$ 1,911	$ 1,427

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

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Available-for-sale Securities, Expected Debt Maturities, Fair Value, Rolling Maturity [Abstract]

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-Topic 320
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Amortized cost of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Weighted average yield of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in second through fifth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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