Discontinued Operations and Assets Held for Sale (Aggregate Balance Sheet of Properties Held for Sale Included in Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Mar. 31, 2014 buildings	Jun. 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		1
Real estate investment, net		$ 24,079
Other assets		5,701
Total assets held-for-sale		29,780
Accrued expenses		363
Other liabilities		175
Total liabilities held-for-sale		538
Continuing Operations [Member]
Discontinued Operations
Real estate investment, net		9,436
Other assets		534
Total assets held-for-sale		9,970
Accrued expenses		188
Other liabilities		175
Total liabilities held-for-sale		363
Discontinued Operations [Member]
Discontinued Operations
Real estate investment, net		14,643
Other assets		5,167
Total assets held-for-sale		19,810
Accrued expenses		175
Other liabilities		0
Total liabilities held-for-sale		$ 175