Discontinued Operations and Assets Held for Sale Impairment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) a	Dec. 31, 2014 USD ($) buildings a $ / sqft	Dec. 31, 2013 USD ($)
Impairment Charges	$ 22,932	$ 49,106	$ 3,777
Acres of Land with Impairment Charge | a	139	442
Number of Real Estate Properties Determined to be Impaired | buildings		6
Fair Value Inputs, Cap Rate	5.57%
Fair Value Measurement With Unobservable Inputs Rental Rate Per Square Foot | $ / sqft		12.50
buildings [Member]
Impairment Charges	$ 3,406	$ 15,406	0
Fair Value Inputs, Cap Rate		8.50%
Land [Member]
Impairment Charges	$ 19,526	$ 33,700	$ 3,777