Variable Interest Entities - Loans Sold to Third-Party Sponsored Securitization Entities (Details) - Nonconsolidated entities - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Summary of loan sale activities
Carrying value of loans sold	$ 29,033	$ 18,065	$ 76,639	$ 60,447
Proceeds received from loan sales as cash	70	5	110	27
Proceeds from loans sales as securities	28,549	17,858	75,331	59,795
Total proceeds received from loan sales	28,619	17,863	75,441	59,822
Gains/(losses) on loan sales	$ 0	$ 0	$ 4	$ 6