Investment Securities - Fair Value and Gross Unrealized Losses on Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Fair Value
Less than 12 months	$ 47,051	$ 7,743
12 months or more	1,659	952
Total	48,710	8,695
Unrealized Losses
Less than 12 months	(3,075)	(106)
12 months or more	(257)	(38)
Total	(3,332)	(144)
Obligations of states and political subdivisions securities
Fair Value
Less than 12 months	1
12 months or more	0
Total	1
Unrealized Losses
Less than 12 months	0
12 months or more	0
Total	0
U.S. Treasury and federal agencies securities
Fair Value
Less than 12 months	1,914
12 months or more	0
Total	1,914
Unrealized Losses
Less than 12 months	(92)
12 months or more	0
Total	(92)
Agency mortgage-backed securities | Residential mortgage backed securities
Fair Value
Less than 12 months	11,515	935
12 months or more	141	161
Total	11,656	1,096
Unrealized Losses
Less than 12 months	(637)	(10)
12 months or more	(30)	(8)
Total	(667)	(18)
Agency mortgage-backed securities | Commercial mortgage-backed securities
Fair Value
Less than 12 months	23,554	2,886
12 months or more	1,037	424
Total	24,591	3,310
Unrealized Losses
Less than 12 months	(1,675)	(49)
12 months or more	(215)	(20)
Total	(1,890)	(69)
Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Fair Value
Less than 12 months	4,693	1,052
12 months or more	1	0
Total	4,694	1,052
Unrealized Losses
Less than 12 months	(341)	(13)
12 months or more	0	0
Total	(341)	(13)
Asset-backed securities and other debt securities
Fair Value
Less than 12 months	5,374	2,870
12 months or more	480	367
Total	5,854	3,237
Unrealized Losses
Less than 12 months	(330)	(34)
12 months or more	(12)	(10)
Total	$ (342)	$ (44)