Investment Securities - Summary of Remaining Contractual Principal Maturities for Held-to-Maturity Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	$ 93,286
Fair Value	77,370	$ 97,227
One Year or Less, Net Carry Value	72
One Year or Less, Fair Value	71
After One Year to Five Years, Net Carry Value	716
After One Year to Five Years, Fair Value	666
After Five Years to Ten Years, Net Carry Value	4,491
After Five Years to Ten Years, Fair Value	3,931
After Ten Years, Net Carry Value	88,007
After Ten Years, Fair Value	72,702
U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	486
Fair Value	433	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	118
After One Year to Five Years, Fair Value	111
After Five Years to Ten Years, Net Carry Value	367
After Five Years to Ten Years, Fair Value	321
After Ten Years, Net Carry Value	0
After Ten Years, Fair Value	0
Agency-issued MBS
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	59,200
Fair Value	49,183	63,676
One Year or Less, Net Carry Value	1
One Year or Less, Fair Value	1
After One Year to Five Years, Net Carry Value	2
After One Year to Five Years, Fair Value	2
After Five Years to Ten Years, Net Carry Value	1,148
After Five Years to Ten Years, Fair Value	1,063
After Ten Years, Net Carry Value	58,049
After Ten Years, Fair Value	48,117
Agency-issued CMO | Fixed rate
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	10,741
Fair Value	8,928	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	87
After One Year to Five Years, Fair Value	83
After Five Years to Ten Years, Net Carry Value	154
After Five Years to Ten Years, Fair Value	146
After Ten Years, Net Carry Value	10,500
After Ten Years, Fair Value	8,699
Agency-issued CMO | Variable rate
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	83
Fair Value	82	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	83
After Ten Years, Fair Value	82
Agency-issued CMBS
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	14,644
Fair Value	12,340	14,721
One Year or Less, Net Carry Value	45
One Year or Less, Fair Value	44
After One Year to Five Years, Net Carry Value	159
After One Year to Five Years, Fair Value	146
After Five Years to Ten Years, Net Carry Value	968
After Five Years to Ten Years, Fair Value	802
After Ten Years, Net Carry Value	13,472
After Ten Years, Fair Value	11,348
Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	7,428
Fair Value	5,817	7,315
One Year or Less, Net Carry Value	25
One Year or Less, Fair Value	25
After One Year to Five Years, Net Carry Value	235
After One Year to Five Years, Fair Value	222
After Five Years to Ten Years, Net Carry Value	1,265
After Five Years to Ten Years, Fair Value	1,114
After Ten Years, Net Carry Value	5,903
After Ten Years, Fair Value	4,456
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Net Carry Value	704
Fair Value	587	$ 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	115
After One Year to Five Years, Fair Value	102
After Five Years to Ten Years, Net Carry Value	589
After Five Years to Ten Years, Fair Value	485
After Ten Years, Net Carry Value	0
After Ten Years, Fair Value	$ 0
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