Investment Securities - Summary of Remaining Contractual Principal Maturities for Held-to-Maturity Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	$ 84,579	$ 97,227
U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	500	615
Residential mortgage-backed securities | Agency-issued mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	54,115	63,676
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations—fixed rate
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	9,884	10,090
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations—variable rate
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	86	101
Agency-issued commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	13,133	14,721
Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	6,240	7,315
After One Year to Five Years, Amortized Cost	199
After Five Years to Ten Years, Amortized Cost	1,294
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	621	$ 709
After One Year to Five Years, Amortized Cost	52
After Five Years to Ten Years, Amortized Cost	653
Held-to-maturity Securities
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	95,814
Fair Value	84,579
One Year or Less, Amortized Cost	63
One Year or Less, Fair Value	62
After One Year to Five Years, Amortized Cost	567
After One Year to Five Years, Fair Value	545
After Five Years to Ten Years, Amortized Cost	4,680
After Five Years to Ten Years, Fair Value	4,329
After Ten Years, Amortized Cost	90,504
After Ten Years, Fair Value	$ 79,643
Held-to-maturity Securities | Lower Limit
Schedule of Held-to-maturity Securities [Line Items]
Mortgage-backed securities contractual maturities (in years)	10 years
Held-to-maturity Securities | Upper Limit
Schedule of Held-to-maturity Securities [Line Items]
Mortgage-backed securities contractual maturities (in years)	30 years
Held-to-maturity Securities | U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	$ 536
Fair Value	500
One Year or Less, Amortized Cost	4
One Year or Less, Fair Value	4
After One Year to Five Years, Amortized Cost	109
After One Year to Five Years, Fair Value	105
After Five Years to Ten Years, Amortized Cost	423
After Five Years to Ten Years, Fair Value	391
After Ten Years, Amortized Cost	0
After Ten Years, Fair Value	0
Held-to-maturity Securities | Residential mortgage-backed securities | Agency-issued mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	61,112
Fair Value	54,115
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year to Five Years, Amortized Cost	4
After One Year to Five Years, Fair Value	4
After Five Years to Ten Years, Amortized Cost	1,102
After Five Years to Ten Years, Fair Value	1,074
After Ten Years, Amortized Cost	60,006
After Ten Years, Fair Value	53,037
Held-to-maturity Securities | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations—fixed rate
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	11,103
Fair Value	9,884
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year to Five Years, Amortized Cost	28
After One Year to Five Years, Fair Value	27
After Five Years to Ten Years, Amortized Cost	239
After Five Years to Ten Years, Fair Value	232
After Ten Years, Amortized Cost	10,836
After Ten Years, Fair Value	9,625
Held-to-maturity Securities | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations—variable rate
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	87
Fair Value	86
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year to Five Years, Amortized Cost	0
After One Year to Five Years, Fair Value	0
After Five Years to Ten Years, Amortized Cost	0
After Five Years to Ten Years, Fair Value	0
After Ten Years, Amortized Cost	87
After Ten Years, Fair Value	86
Held-to-maturity Securities | Agency-issued commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	14,821
Fair Value	13,133
One Year or Less, Amortized Cost	32
One Year or Less, Fair Value	31
After One Year to Five Years, Amortized Cost	175
After One Year to Five Years, Fair Value	165
After Five Years to Ten Years, Amortized Cost	969
After Five Years to Ten Years, Fair Value	858
After Ten Years, Amortized Cost	13,645
After Ten Years, Fair Value	12,079
Held-to-maturity Securities | Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	7,450
Fair Value	6,240
One Year or Less, Amortized Cost	27
One Year or Less, Fair Value	27
After One Year to Five Years, Fair Value	196
After Five Years to Ten Years, Fair Value	1,201
After Ten Years, Amortized Cost	5,930
After Ten Years, Fair Value	4,816
Held-to-maturity Securities | Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	705
Fair Value	621
One Year or Less, Amortized Cost	0
One Year or Less, Fair Value	0
After One Year to Five Years, Fair Value	48
After Five Years to Ten Years, Fair Value	573
After Ten Years, Amortized Cost	0
After Ten Years, Fair Value	$ 0