Premises and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Operating Leases, Rent Expense, Net	$ 179	$ 201	$ 202
Depreciation, Depletion and Amortization	333	299	290
Amortization Of Deferred Gain On Sale Lease Back Of Premises	6	17	$ 43
Sale Leaseback Transaction, Deferred Gain, Gross	$ 42	$ 49
Lessee, Operating Lease, Term of Contract	20 years