Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Allowance for loan losses	$ 7,270	$ 3,400
Employee benefits	1,104	1,039
Accrued expenses and other	3,332	2,767
Non-U.S. operations	849	949
Tax attribute carryforwards	757	605
Gross deferred tax assets	13,312	8,760
Valuation allowance	(560)	(557)
Deferred tax assets, net of valuation allowance	12,752	8,203
Deferred tax liabilities
Depreciation and amortization	3,329	2,852
Mortgage servicing rights, net of hedges	2,184	2,354
Leasing transactions	5,124	5,598
Other, net	6,025	4,683
Gross deferred tax liabilities	16,662	15,487
Net deferred tax (liabilities)/assets	(3,910)	$ (7,284)
FTC carryforwards	444
U.S. federal
Deferred tax liabilities
NOL carryforwards	799
Other tax attributes	393
Non-U.S.
Deferred tax liabilities
NOL carryforwards	139
State and local
Deferred tax liabilities
NOL carryforwards	$ 1,100