Annual report pursuant to Section 13 and 15(d)

Accounting Policies - Real Estate and Depreciation (Details)

v2.4.1.9
Accounting Policies - Real Estate and Depreciation (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]      
Real estate depreciation $ 71,400,000us-gaap_Depreciation $ 63,400,000us-gaap_Depreciation $ 61,100,000us-gaap_Depreciation
Total interest expense from continuing operations 61,927,000us-gaap_InterestCostsIncurred 64,809,000us-gaap_InterestCostsIncurred 62,315,000us-gaap_InterestCostsIncurred
Capitalized interest 2,142,000us-gaap_InterestCostsIncurredCapitalized 1,236,000us-gaap_InterestCostsIncurredCapitalized 1,688,000us-gaap_InterestCostsIncurredCapitalized
Interest expense from continuing operations, net of capitalized interest $ 59,785,000us-gaap_InterestExpense $ 63,573,000us-gaap_InterestExpense $ 60,627,000us-gaap_InterestExpense
Minimum [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 3 years    
Minimum [Member] | Building [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 28 years    
Minimum [Member] | Building and Building Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 3 years    
Maximum [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 50 years    
Maximum [Member] | Building [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 50 years    
Maximum [Member] | Building and Building Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Useful Life 30 years