Bank Premises & Equipment (Bank Premises and Equipment) (Parenthetical) (Detail) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Bank Premises and Equipment
Land and improvements	[1]	$ 647	$ 663
Branches and undeveloped parcels of land
Bank Premises and Equipment
Land and improvements		$ 91	$ 92

[1] (a ) At June 30, 2017 and December 31, 2016 , land and improvements , buildings and construction in progress included $ 91 and $ 92 , respectively, associated w ith parcels of undeveloped land intended for future branch expansion.