Bank Premises & Equipment (Bank Premises and Equipment) (Parenthetical) (Detail) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Bank Premises and Equipment
Land and improvements	[1]	$ 660	$ 586
Branches and undeveloped parcels of land
Bank Premises and Equipment
Land and improvements		$ 57	$ 55

[1] At March 31, 2019 and December 31, 2018 , land and improvements , buildings and construction in progress included $ 57 and $ 55 , respectively, associated w ith parcels of undeveloped land intended for future branch expansion.