Investment Securities - Summary of Remaining Contractual Principal Maturities for Held-to-Maturity Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	$ 97,227	$ 17,217
U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	615	421
Residential mortgage-backed securities | Agency-issued mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	63,676	7,978
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations - fixed rate
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	10,090	1,758
Residential mortgage-backed securities | Variable rate
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	101	138
Agency-issued commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	14,721	3,067
Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	7,315	$ 3,855
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	709
Held-to-maturity securities
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	98,195
Fair Value	97,227
One Year or Less - Net Carry Value	49
One Year or Less - Fair Value	49
After One Year to Five Years - Net Carry Value	574
After One Year to Five Years - Fair Value	580
After Five Years to Ten Years - Net Carry Value	4,393
After Five Years to Ten Years - Fair Value	4,479
After Ten Years - Net Carry Value	93,179
After Ten Years - Fair Value	92,119
Held-to-maturity securities | U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	609
Fair Value	615
One Year or Less - Net Carry Value	1
One Year or Less - Fair Value	1
After One Year to Five Years - Net Carry Value	133
After One Year to Five Years - Fair Value	135
After Five Years to Ten Years - Net Carry Value	475
After Five Years to Ten Years - Fair Value	479
After Ten Years - Net Carry Value	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	64,439
Fair Value	63,676
One Year or Less - Net Carry Value	0
One Year or Less - Fair Value	0
After One Year to Five Years - Net Carry Value	7
After One Year to Five Years - Fair Value	7
After Five Years to Ten Years - Net Carry Value	806
After Five Years to Ten Years - Fair Value	828
After Ten Years - Net Carry Value	63,626
After Ten Years - Fair Value	62,841
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	10,226
Fair Value	10,090
One Year or Less - Net Carry Value	0
One Year or Less - Fair Value	0
After One Year to Five Years - Net Carry Value	14
After One Year to Five Years - Fair Value	14
After Five Years to Ten Years - Net Carry Value	316
After Five Years to Ten Years - Fair Value	319
After Ten Years - Net Carry Value	9,896
After Ten Years - Fair Value	9,757
Held-to-maturity securities | Residential mortgage-backed securities | Variable rate
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	100
Fair Value	101
One Year or Less - Net Carry Value	0
One Year or Less - Fair Value	0
After One Year to Five Years - Net Carry Value	0
After One Year to Five Years - Fair Value	0
After Five Years to Ten Years - Net Carry Value	0
After Five Years to Ten Years - Fair Value	0
After Ten Years - Net Carry Value	100
After Ten Years - Fair Value	101
Held-to-maturity securities | Agency-issued commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	14,959
Fair Value	14,721
One Year or Less - Net Carry Value	0
One Year or Less - Fair Value	0
After One Year to Five Years - Net Carry Value	211
After One Year to Five Years - Fair Value	209
After Five Years to Ten Years - Net Carry Value	971
After Five Years to Ten Years - Fair Value	982
After Ten Years - Net Carry Value	13,777
After Ten Years - Fair Value	13,530
Held-to-maturity securities | Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	7,156
Fair Value	7,315
One Year or Less - Net Carry Value	48
One Year or Less - Fair Value	48
After One Year to Five Years - Net Carry Value	176
After One Year to Five Years - Fair Value	182
After Five Years to Ten Years - Net Carry Value	1,152
After Five Years to Ten Years - Fair Value	1,195
After Ten Years - Net Carry Value	5,780
After Ten Years - Fair Value	5,890
Held-to-maturity securities | Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	706
Fair Value	709
One Year or Less - Net Carry Value	0
One Year or Less - Fair Value	0
After One Year to Five Years - Net Carry Value	33
After One Year to Five Years - Fair Value	33
After Five Years to Ten Years - Net Carry Value	673
After Five Years to Ten Years - Fair Value	676
After Ten Years - Net Carry Value	0
After Ten Years - Fair Value	$ 0
Lower Limit | Held-to-maturity securities
Schedule of Held-to-maturity Securities [Line Items]
Mortgage-backed securities contractual maturities (in years)	10 years
Upper Limit | Held-to-maturity securities
Schedule of Held-to-maturity Securities [Line Items]
Mortgage-backed securities contractual maturities (in years)	30 years