Bank Premises and Equipment (Bank Premises and Equipment (Parenthetical) (Detail)) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Land and improvements	[1]	$ 639	$ 586
Branches and undeveloped parcels of land
Property, Plant and Equipment
Land and improvements		$ 51	$ 55

[1] At December 31, 2019 and 2018, land and improvements, buildings and construction in progress included $51 and $55, respectively, associated with parcels of undeveloped land intended for future branch expansion.