Real Estate - Investments in Real Estate Properties (Detail) ft² in Thousands, $ in Thousands	Jun. 30, 2016 USD ($) ft² Buildings	Dec. 31, 2015 USD ($) ft² Buildings
Real Estate Properties [Line Items]
Total investments in real estate properties	$ 27,556,410	$ 27,521,368
Less accumulated depreciation	3,521,198	3,274,284
Net investments in real estate properties	$ 24,035,212	$ 24,247,084
Improved Land [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	0	0
Number of buildings | Buildings	0	0
Total investments in real estate properties	$ 5,945,476	$ 5,874,052
Building and Improvements [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	333,647	333,830
Number of buildings | Buildings	1,825	1,872
Total investments in real estate properties	$ 17,967,859	$ 17,861,693
Development Portfolio, Including Cost of Land: Pre-stabilized [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	9,429	12,598
Number of buildings | Buildings	22	28
Total investments in real estate properties	$ 856,407	$ 918,099
Properties Under Development [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	16,591	19,630
Number of buildings | Buildings	60	63
Total investments in real estate properties	$ 914,364	$ 954,804
Land [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	7,013	7,404
Number of buildings | Buildings	0	0
Total investments in real estate properties	$ 1,322,214	$ 1,359,794
Other Real Estate Investments [Member]
Real Estate Properties [Line Items]
Square Feet and Acres | ft²	0	0
Number of buildings | Buildings	0	0
Total investments in real estate properties	$ 550,090	$ 552,926