Income Taxes - Significant Components of Deferred Tax Assets and Liabilities Included in "Accrued Income and Other Assets" and "Accrued Expense and Other Liabilities" (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Allowance for loan and lease losses	$ 236	$ 232
Employee benefits	164	170
Net unrealized securities losses	0	144
Federal net operating losses and credits	81	34
Fair value adjustments	21	41
Non-tax accruals	61	80
Operating lease liabilities	178
State net operating losses and credits	1	3
Other	245	221
Gross deferred tax assets	987	925
Less: Valuation Allowance	0	11
Total deferred tax assets	987	914
Leasing transactions	628	531
Net unrealized securities gains	117	0
Operating lease right-of-use assets	156
Other	175	161
Total deferred tax liabilities	1,076	692
Net deferred tax assets (liabilities)	$ (89)
Net deferred tax assets (liabilities)		$ 222