Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2023	Dec. 31, 2022
Securities available for sale
Due in 1 year or less	$ 1,214
Due after 1 year through 5 years	8,195
Due after 5 years through 10 years	4,704
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	64,299
Securities available for sale	78,412	$ 76,919
Amortized cost of securities available for sale
Due in 1 year or less	1,219
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost	8,452
Due after 5 years through 10 years	5,204
Due > 10 Years	73,570
Amortized Cost	$ 88,445	87,047
Weighted average yield for securities available for sale
Due in 1 Year or Less	4.16%
Due > 1 Year through 5 Years	3.56%
Due > 5 Years through 10 Years	3.00%
Due > 10 Years	2.77%
Total weighted average yield	2.88%
U.S. Treasury securities
Securities available for sale
Due in 1 year or less	$ 753
Due after 1 year through 5 years	4,357
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	5,110	5,041
Amortized cost of securities available for sale
Amortized Cost	5,197	5,129
RMBS, Agency
Securities available for sale
Due in 1 year or less	0
Due after 1 year through 5 years	79
Due after 5 years through 10 years	1,181
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	61,544
Securities available for sale	62,804	61,852
Amortized cost of securities available for sale
Amortized Cost	72,085	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	1
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	713
Securities available for sale	714	737
Amortized cost of securities available for sale
Amortized Cost	631	653
RMBS
Securities available for sale
Due in 1 year or less	0
Due after 1 year through 5 years	79
Due after 5 years through 10 years	1,182
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	62,257
Securities available for sale	63,518	62,589
Amortized cost of securities available for sale
Amortized Cost	$ 72,716	71,865
Weighted average yield for securities available for sale
Weighted-average expected life	6 years 10 months 24 days
CMBS, Agency
Securities available for sale
Due in 1 year or less	$ 49
Due after 1 year through 5 years	2,429
Due after 5 years through 10 years	3,492
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	2,042
Securities available for sale	8,012	7,870
Amortized cost of securities available for sale
Amortized Cost	$ 8,757	8,626
Weighted average yield for securities available for sale
Weighted-average expected life	4 years 8 months 12 days
Other securities
Securities available for sale
Due in 1 year or less	$ 412
Due after 1 year through 5 years	1,330
Due after 5 years through 10 years	30
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	0
Securities available for sale	1,772	1,419
Amortized cost of securities available for sale
Amortized Cost	$ 1,775	$ 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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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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