Premises and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Capital Leased Assets, Gross	$ 3	$ 4
Operating Leases, Rent Expense, Net	200	206	$ 220
Depreciation, Depletion and Amortization	175	176	185
Amortization Of Deferred Gain On Sale Lease Back Of Premises	54	53	$ 58
Sale Leaseback Transaction, Deferred Gain, Gross	$ 108	$ 162