Accounting Policies - Real Estate and Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Real estate depreciation	$ 80,700	$ 71,400	$ 63,400
Total interest expense from continuing operations	60,204	61,927	64,809
Capitalized interest	658	2,142	1,236
Interest expense from continuing operations, net of capitalized interest	$ 59,546	$ 59,785	$ 63,573
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