Investment Securities - Gains and Losses Recognized in Income from Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Available-for-sale debt and other securities:
Realized gains	$ 3	$ 16	$ 15	$ 24
Realized losses	(3)	(3)	(12)	(14)
Impairment losses	0	(12)	0	(19)
Net realized gains (losses) on available-for-sale debt and other securities	0	1	3	(9)
Trading debt securities:
Net realized losses	(1)	0	(2)	(1)
Net unrealized gains (losses)	0	(1)	11	0
Net trading debt securities gains (losses)	(1)	(1)	9	(1)
Equity securities:
Net realized gains	1	2	1	6
Net unrealized (losses) gains	(39)	(3)	(99)	14
Net equity securities (losses) gains	(38)	(1)	(98)	20
Total (losses) gains recognized in income from available-for-sale debt and other securities, trading debt securities and equity securities	(39)	(1)	(86)	10
Commercial Banking Revenue and Wealth and Asset Management Revenue
Investment Holdings [Line Items]
Securities gains (losses)	$ (1)	$ (1)	$ (4)	$ (4)