Real Estate - Summary of Acquisition (Detail) ft² in Thousands, $ in Thousands	Dec. 31, 2016 USD ($) ft² Property	Dec. 31, 2015 USD ($) ft² Property	Dec. 31, 2014 USD ($) ft² Property	Dec. 31, 2013 USD ($)
Business Acquisition [Line Items]
Real estate acquisition value	$ 25,375,539	$ 25,608,648	$ 20,109,432	$ 18,822,081
Acquisitions of Properties from Third Parties [Member]
Business Acquisition [Line Items]
Number of buildings | Property	9	52	8
Square feet | ft²	1,823	7,375	1,004
Real estate acquisition value	$ 411,706	$ 1,042,562	$ 548,201