Bank Premises & Equipment (Bank Premises and Equipment) (Parenthetical) (Detail) - USD ($)		Jun. 30, 2016	Dec. 31, 2015
Bank Premises and Equipment
Land and improvements	[1]	$ 676,000,000	$ 685,000,000
Branches and undeveloped parcels of land
Bank Premises and Equipment
Land and improvements		$ 102,000,000	$ 102,000,000

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