Real Estate - Summary of Acquisition (Detail) ft² in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($) ft² Property	Dec. 31, 2013 USD ($) ft² Property	Dec. 31, 2015 USD ($) ft² Property	Dec. 31, 2012 USD ($)
Business Acquisition [Line Items]
Real estate acquisition value	$ 20,109,432	$ 18,822,081	$ 25,608,648	$ 23,559,891
Third Parties [Member]
Business Acquisition [Line Items]
Number of buildings | Property	8	12	52
Square feet | ft²	1,004	3,262	7,375
Real estate acquisition value	$ 78,314	$ 146,331	$ 829,598
Unconsolidated Co-investment Ventures [Member]
Business Acquisition [Line Items]
Number of buildings | Property	231	58
Square feet | ft²	45,663	16,319
Real estate acquisition value	$ 2,658,252	$ 1,141,128
Gains on revaluation of equity investments upon acquisition of a controlling interest	$ 201,319	$ 34,787