Investment Securities - Summary of Remaining Contractual Principal Maturities for Available-for-Sale Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	$ 26,711	$ 27,221
One Year or Less	977
After One Year to Five Years	15,313
After Five Years to Ten Years	3,069
After Ten Years	7,352
U.S. treasury securities
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	16,845	15,850
One Year or Less	936
After One Year to Five Years	15,133
After Five Years to Ten Years	776
After Ten Years	0
U.S. agency debentures
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	100	196
One Year or Less	0
After One Year to Five Years	34
After Five Years to Ten Years	66
After Ten Years	0
Foreign government debt securities
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	913	61
One Year or Less	41
After One Year to Five Years	46
After Five Years to Ten Years	826
After Ten Years	0
Agency-issued MBS
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	6,683	8,589
One Year or Less	0
After One Year to Five Years	0
After Five Years to Ten Years	45
After Ten Years	6,638
Agency-issued CMO—fixed rate
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	714	982
One Year or Less	0
After One Year to Five Years	0
After Five Years to Ten Years	0
After Ten Years	714
Agency-issued CMBS
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	1,456	$ 1,543
One Year or Less	0
After One Year to Five Years	100
After Five Years to Ten Years	1,356
After Ten Years	$ 0
Available-for-sale Securities | Lower Limit
Debt Securities, Available-for-sale [Line Items]
Mortgage-backed securities contractual maturities (in years)	10 years
Available-for-sale Securities | Upper Limit
Debt Securities, Available-for-sale [Line Items]
Mortgage-backed securities contractual maturities (in years)	30 years