Summary of Property and Equipment (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Land and land improvements	$ 2,072	$ 2,047
Buildings and leasehold improvements	13,658	13,483
Furniture and equipment	2,362	2,377
Construction in progress	94	86
Property, Plant and Equipment, Gross, Total	18,186	17,993
Less accumulated depreciation and amortization	(8,172)	(7,848)
Property and equipment, net	$ 10,014	$ 10,145