v3.8.0.1
Real Estate - Investments in Real Estate Properties (Detail)
ft² in Thousands, $ in Thousands
Sep. 30, 2017
USD ($)
ft²
a
Buildings
Dec. 31, 2016
USD ($)
ft²
a
Buildings
Real Estate Properties [Line Items]    
Total investments in real estate properties $ 25,977,157 $ 27,119,330
Less accumulated depreciation 3,977,667 3,758,372
Net investments in real estate properties $ 21,999,490 $ 23,360,958
Improved Land [Member]    
Real Estate Properties [Line Items]    
Square Feet | ft² 0 0
Number of buildings | Buildings 0 0
Total investments in real estate properties $ 5,826,773 $ 6,037,543
Building and Improvements [Member]    
Real Estate Properties [Line Items]    
Square Feet | ft² 298,240 331,210
Number of buildings | Buildings 1,566 1,776
Total investments in real estate properties $ 16,829,500 $ 17,905,914
Development Portfolio, Including Cost of Land: Pre-stabilized [Member]    
Real Estate Properties [Line Items]    
Square Feet | ft² 7,394 8,256
Number of buildings | Buildings 24 29
Total investments in real estate properties $ 441,235 $ 798,233
Properties Under Development [Member]    
Real Estate Properties [Line Items]    
Square Feet | ft² 22,189 19,539
Number of buildings | Buildings 55 60
Total investments in real estate properties $ 1,059,764 $ 633,849
Land [Member]    
Real Estate Properties [Line Items]    
Square Feet | a 5,871 5,892
Total investments in real estate properties $ 1,313,268 $ 1,218,904
Other Real Estate Investments [Member]    
Real Estate Properties [Line Items]    
Square Feet | ft² 0 0
Number of buildings | Buildings 0 0
Total investments in real estate properties $ 506,617 $ 524,887