Employee Share-based Incentives - Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Cost of prior grants of RSUs, performance share units (“PSUs”) and stock options that are amortized over their applicable vesting periods	$ 280	$ 276	$ 636	$ 610
Accrual of estimated costs of share-based awards to be granted in future periods, predominantly those to full-career eligible employees	463	526	1,011	836
Total noncash compensation expense related to employee share-based incentive plans	$ 743	$ 802	$ 1,647	$ 1,446