Premises and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Land	$ 321	$ 320
Buildings and Improvements, Gross	1,047	1,028
Leasehold improvements	691	645
Furniture and equipment	1,430	1,492
Construction in progress	488	357
Property, Plant and Equipment, Gross, Total	3,977	3,842
Less accumulated depreciation and amortization	2,243	2,286
Premises and equipment	$ 1,734	$ 1,556
Building and Building Improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year	1 year
Building and Building Improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years	40 years
Leasehold Improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year	1 year
Leasehold Improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years	30 years
Furniture and Fixtures | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year	1 year
Furniture and Fixtures | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years	20 years