v2.4.0.8
Real Estate - Real Estate Assets (Detail) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2014
Jun. 30, 2014
sqft
Dec. 31, 2013
Real Estate Properties [Line Items]      
Square Feet / Acres   12,600,000  
Industrial operating properties:      
Total investments in real estate properties $ 19,466,582   $ 20,824,477
Less accumulated depreciation 2,695,745   2,568,998
Net investments in real estate properties 16,770,837   18,255,479
Improved Land [Member]
     
Industrial operating properties:      
Total investments in real estate properties 3,641,571   4,074,647
Building and Improvements [Member]
     
Real Estate Properties [Line Items]      
Square Feet / Acres 241,104,000   267,097,000
Number of buildings 1,415   1,610
Industrial operating properties:      
Total investments in real estate properties 12,514,097   13,726,417
Development Portfolio, Including Cost of Land: Pre-stabilized [Member]
     
Real Estate Properties [Line Items]      
Square Feet / Acres 5,105,000   4,491,000
Number of buildings 15   11
Industrial operating properties:      
Total investments in real estate properties 391,055   204,022
Properties Under Development [Member]
     
Real Estate Properties [Line Items]      
Square Feet / Acres 21,158,000   18,587,000
Number of buildings 51   46
Industrial operating properties:      
Total investments in real estate properties 925,415   816,995
Land [Member]
     
Real Estate Properties [Line Items]      
Square Feet / Acres 9,226,000   9,747,000
Industrial operating properties:      
Total investments in real estate properties 1,533,590   1,516,166
Other Real Estate Investments [Member]
     
Industrial operating properties:      
Total investments in real estate properties $ 460,854   $ 486,230