Investment Securities - Gains and Losses Recognized in Income from Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Available-for-sale debt and other securities:
Realized gains	$ 1	$ 3	$ 34	$ 15
Realized losses	0	(3)	(30)	(12)
Impairment losses	(1)	0	(5)	0
Net realized (losses) gains on available-for-sale debt and other securities	0	0	(1)	3
Trading debt securities:
Net realized losses	0	(1)	0	(2)
Net unrealized gains	0	0	2	11
Net trading debt securities gains (losses)	0	(1)	2	9
Equity securities:
Net realized gains	2	1	3	1
Net unrealized losses	(9)	(39)	(1)	(99)
Net equity securities gains (losses)	(7)	(38)	2	(98)
Total (losses) gains recognized in income from available-for-sale debt and other securities, trading debt securities and equity securities	7	39	(3)	86
Commercial Banking Revenue and Wealth and Asset Management Revenue
Equity securities:
Total (losses) gains recognized in income from available-for-sale debt and other securities, trading debt securities and equity securities	$ (2)	$ 1	$ (3)	$ 4