Bank Premises and Equipment (Bank Premises and Equipment) (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment
Land and improvements	[1]	$ 634	$ 639
Buildings	[1]	1,564	1,575
Equipment		2,151	2,126
Leasehold improvements		438	432
Construction in progress	[1]	92	85
Land and improvements held for sale		15	8
Buildings held for sale		20	18
Equipment held for sale		1	1
Accumulated depreciation and amortization		(2,906)	(2,889)
Total bank premises and equipment		$ 2,009	$ 1,995

[1] At March 31, 2020 and December 31, 2019, land and improvements, buildings and construction in progress included $53 and $51, respectively, associated with parcels of undeveloped land intended for future branch expansion.