v2.4.0.6
Real Estate (Details) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Industrial Operating Properties    
Improved land $ 5,525,407 $ 4,813,145
Buildings and improvements 17,916,987 16,739,403
Development portfolio, including cost of land 656,561 860,531
Land 1,881,062 1,984,233
Other real estate investments 442,280 390,225
Total investments in real estate properties 26,422,297 24,787,537
Less accumulated depreciation 2,256,101 2,157,907
Net investments in real estate properties $ 24,166,196 $ 22,629,630