Acquisitions - Additional Informtions (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Business acquisition, total purchase price	$ 1,870
Total purchase price	1,872	[1]
Sellers Affiliated with Blackstone and an Unrelated Third Party [Member]
Business Acquisition [Line Items]
Business acquisition, transaction costs	26,000
Blackstone Group L.P. [Member]
Business Acquisition [Line Items]
Total purchase price	$ 1,760

[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.