Other Assets (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Assets [Line Items]
Amortization period of acquired finite-lived intangible assets	6 years	7 years
Foreign deferred tax liabilities	$ 98	$ 81
Tax Credit Investments - Affordable Housing partnerships	1,018	798
Other Assets (Textuals) [Abstract]
Accumulated goodwill impairment losses	220	220
Amortization expense	207	194	$ 183
Community Reinvestment Act Tax Credit Investments	1,023	824
Other Expense [Member]
Other Assets [Line Items]
Loss from Affordable Housing Projects Equity Method Investments	112	43
Income Tax Provision [Member]
Other Assets [Line Items]
QAH Tax Credits for equity method losses	74	63
Other Liabilities [Member]
Other Assets [Line Items]
QAH Investment Commitment	373
Variable Interest Enterprise [Member]
Other Assets [Line Items]
Affordable Housing Program Off Balance Sheet Obligation	66
Tax Credit Investments - Affordable Housing partnerships	933	$ 701
Variable Interest Enterprise [Member] | Other Liabilities [Member]
Other Assets [Line Items]
QAH Investment Commitment	$ 352
Earliest Year [Member]
Other Assets [Line Items]
Affordable Housing Tax Credits Commitment Year To Be Paid	2018
Latest Year [Member]
Other Assets [Line Items]
Affordable Housing Tax Credits Commitment Year To Be Paid	2032