Employee Share-Based Incentives - Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncash compensation expense related to employee stock-based incentive plans
Cost of prior grants of RSUs, PSUs, SARs and stock options that are amortized over their applicable vesting periods	$ 1,101	$ 1,141	$ 1,241
Accrual of estimated costs of share-based awards to be granted in future periods including those to full-career eligible employees	1,350	1,115	1,081
Total noncash compensation expense related to employee share-based incentive plans	2,451	$ 2,256	$ 2,322
Compensation cost related to unvested awards not charged to net income	$ 664
Weighted-average period for cost expected to be amortized into compensation expense	1 year 7 months 6 days