Investment Securities - Contractual Maturities and Weighted-Average Yields of Securities (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Securities available for sale
Due in 1 year or less	$ 6,135
Due after 1 year through 5 years	8,595
Due after 5 years through 10 years	5,233
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	69,113
Securities available for sale	89,076	$ 95,261
Amortized cost of securities available for sale
Due in 1 year or less	6,130
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost	8,694
Due after 5 years through 10 years	5,401
Due > 10 Years	72,748
Amortized Cost	$ 92,973
Weighted average yield for securities available for sale
Due in 1 Year or Less	0.39%
Due > 1 Year through 5 Years	0.89%
Due > 5 Years through 10 Years	1.91%
Due > 10 Years	1.96%
Total weighted average yield	1.75%
U.S. Treasury securities
Securities available for sale
Due in 1 year or less	$ 5,338
Due after 1 year through 5 years	4,159
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	9,497	9,442
RMBS, Agency
Securities available for sale
Due in 1 year or less	0
Due after 1 year through 5 years	124
Due after 5 years through 10 years	1,070
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	66,330
Securities available for sale	67,524	72,620
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	0
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	901
Securities available for sale	901	996
RMBS
Securities available for sale
Due in 1 year or less	0
Due after 1 year through 5 years	124
Due after 5 years through 10 years	1,070
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	67,231
Securities available for sale	$ 68,425	73,616
Weighted average yield for securities available for sale
Weighted-average expected life	6 years 6 months
CMBS, Agency
Securities available for sale
Due in 1 year or less	$ 506
Due after 1 year through 5 years	2,117
Due after 5 years through 10 years	3,860
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	1,882
Securities available for sale	$ 8,365	9,369
Weighted average yield for securities available for sale
Weighted-average expected life	5 years 4 months 24 days
Other securities
Securities available for sale
Due in 1 year or less	$ 291
Due after 1 year through 5 years	2,195
Due after 5 years through 10 years	303
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	0
Securities available for sale	$ 2,789	$ 2,834

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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Debt Maturities, Available-for-Sale, Weighted Average Expected Life

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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