Real Estate - Summary of Acquisition (Detail) (USD $) In Thousands, unless otherwise specified					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Unconsolidated Properties [Member] sqft Property	Dec. 31, 2012 Unconsolidated Properties [Member] sqft Property	Dec. 31, 2011 Unconsolidated Properties [Member] sqft Property	Dec. 31, 2013 Third Parties [Member] Property sqft	Dec. 31, 2012 Third Parties [Member] Property sqft	Dec. 31, 2011 Third Parties [Member] sqft Property
Business Acquisition [Line Items]
Number of properties					58	215	233	12	12	8
Square feet					16,319,000	46,277,000	53,603,000	3,262,000	1,622,000	1,498,000
Real estate acquisition value	$ 18,822,081	$ 23,559,891	$ 22,413,079	$ 11,080,161	$ 1,141,128	$ 2,294,892	$ 4,591,017	$ 146,331	$ 77,397	$ 86,851
Net gains					$ 34,787	$ 286,335	$ 99,369