Discontinued Operations, Assets Held for Sale and Impairments (Aggregate Balance Sheet of Properties Held for Sale Included in Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2014 buildings	Sep. 30, 2014 buildings
Discontinued Operations
Discontinued Operation, Number of Real Estate Properties Held for Sale	3	1
Continuing Operations, Number of In-service Properties Held for Sale		2
Real estate investment, net		$ 29,583
Other assets		5,831
Total assets held-for-sale		35,414
Accrued expenses		618
Other liabilities		87
Total liabilities held-for-sale		705
Continuing Operations [Member]
Discontinued Operations
Real estate investment, net		14,940
Other assets		473
Total assets held-for-sale		15,413
Accrued expenses		356
Other liabilities		87
Total liabilities held-for-sale		443
Discontinued Operations [Member]
Discontinued Operations
Real estate investment, net		14,643
Other assets		5,358
Total assets held-for-sale		20,001
Accrued expenses		262
Other liabilities		0
Total liabilities held-for-sale		$ 262