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Investment Securities - Components of Held-to-Maturity Investment Securities (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 95,820	$ 98,202
Unrealized Gains	3	368
Unrealized Losses	(11,244)	(1,343)
Fair Value	84,579	97,227
Allowance for Credit Losses	6	7	$ 5	$ 1	$ 1
U.S. agency debentures
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	536	609
Unrealized Gains	0	8
Unrealized Losses	(36)	(2)
Fair Value	500	615
Allowance for Credit Losses	0	0
Residential mortgage-backed securities \| Agency-issued mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	61,112	64,439
Unrealized Gains	0	124
Unrealized Losses	(6,997)	(887)
Fair Value	54,115	63,676
Allowance for Credit Losses	0	0
Residential mortgage-backed securities \| Agency-issued collateralized mortgage obligations—fixed rate
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	11,103	10,226
Unrealized Gains	0	9
Unrealized Losses	(1,219)	(145)
Fair Value	9,884	10,090
Allowance for Credit Losses	0	0
Residential mortgage-backed securities \| Agency-issued collateralized mortgage obligations—variable rate
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	87	100
Unrealized Gains	0	1
Unrealized Losses	(1)	0
Fair Value	86	101
Allowance for Credit Losses	0	0
Agency-issued commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,821	14,959
Unrealized Gains	0	39
Unrealized Losses	(1,688)	(277)
Fair Value	13,133	14,721
Allowance for Credit Losses	0	0
Municipal bonds and notes
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	7,451	7,157
Unrealized Gains	3	185
Unrealized Losses	(1,214)	(27)
Fair Value	6,240	7,315
Allowance for Credit Losses	1	1
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	710	712
Unrealized Gains	0	2
Unrealized Losses	(89)	(5)
Fair Value	621	709
Allowance for Credit Losses	$ 5	$ 6