Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Deferred tax assets - Allowance for loan and lease losses	$ 631	$ 976
Deferred tax assets - Compensation and benefits	223	548
Deferred tax assets - Partnership investments	173	307
Deferred tax assets - Loss and credit carryforward	301	460
Deferred tax assets - Accrued expenses	284	505
Deferred tax assets - Other	131	252
Total gross deferred tax assets	1,743	3,048
Valuation allowance	(40)	(75)
Total deferred tax assets	1,703	2,973
Deferred tax liabilities - Leasing	1,034	1,374
Deferred tax liabilities - Goodwill and intangibles	197	312
Deferred tax liabilities - Fixed assets	206	391
Deferred tax liabilities - Mortgage Servicing Rights	146	246
Deferred tax liabilities - Net unrealized gains on securities and financial instruments	155	284
Deferred tax liabilities - BlackRock basis difference	1,594	2,361
Deferred tax liabilities - Other	345	371
Total deferred tax liabilities	3,677	5,339
Net deferred tax liability	$ 1,974	$ 2,366