Bank Premises & Equipment (Bank Premises and Equipment) (Parenthetical) (Detail) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Bank Premises and Equipment
Land and improvements	[1]	$ 663	$ 685
Branches and undeveloped parcels of land
Bank Premises and Equipment
Land and improvements		$ 94	$ 102

[1] (a ) At September 30, 2016 and December 31, 2015 , land and improvements included $ 94 and $ 102 , respectively, associated w ith parcels of undeveloped land intended for future branch expansion.