Schedule III - Real Estate and Accumulated Depreciation - Change in Total Cost of Properties (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate And Accumulated Depreciation Disclosure [Abstract]
Balance at beginning of period		$ 10,310	$ 10,253	$ 8,220
Additions during period:
Acquisitions	[1]			1,872
Capital expenditures		198	224	224
Deductions during period:
Transfers to assets held for sale		(46)
Dispositions, including casualty losses and impairment loss on planned dispositions		(236)	(161)	(3)
Foreign exchange effect		23	(6)	(60)
Balance at end of period		$ 10,249	$ 10,310	$ 10,253

[1] In 2015, as part of a tax deferred exchange of real property, certain properties from sellers affiliated with The Blackstone Group L.P., a related party at the time of the transaction, were acquired for a total purchase price of $1.76 billion.