Real Estate Investments - Summary of Properties Classified as Held for Sale Included in Continuing Operations (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
ASSETS HELD FOR SALE
Operating properties		$ 17,622
Accumulated depreciation		(6,009)
Operating real estate investments, net		11,613
Construction-in-progress		675
Total real estate investments, net		12,288
Other assets		20
Total assets held for sale, net		12,308	$ 584,365
LIABILITIES HELD FOR SALE
Other liabilities		11
Total liabilities held for sale		11	$ 2,151
Held for Sale Properties Included in Continuing Operations [Member] | 1120 Executive Boulevard [Member]
ASSETS HELD FOR SALE
Operating properties	[1]	13,256
Accumulated depreciation	[1]	(6,005)
Operating real estate investments, net	[1]	7,251
Construction-in-progress	[1]	675
Total real estate investments, net	[1]	7,926
Other assets	[1]	20
Total assets held for sale, net	[1]	7,946
LIABILITIES HELD FOR SALE
Other liabilities	[1]	11
Total liabilities held for sale	[1]	11
Held for Sale Properties Included in Continuing Operations [Member] | Oakland Lot B [Member]
ASSETS HELD FOR SALE
Operating properties	[2]	4,366
Accumulated depreciation	[2]	(4)
Operating real estate investments, net	[2]	4,362
Construction-in-progress	[2]	0
Total real estate investments, net	[2]	4,362
Other assets	[2]	0
Total assets held for sale, net	[2]	4,362
LIABILITIES HELD FOR SALE
Other liabilities	[2]	0
Total liabilities held for sale	[2]	$ 0

[1] On June 1, 2016, the Company entered into an agreement to sell an office property containing 95,183 square feet at 1120 Executive Boulevard located in Mount Laurel, New Jersey. As of June 30, 2016, the Company determined that the sale of the property was probable and classified this property as held for sale in accordance with applicable accounting standards for long lived assets. At such date, the carrying value of the property exceeded the fair value less the anticipated costs of sale. As a result, the Company recognized an impairment loss totaling approximately $1.8 million during the three-month period ended June 30, 2016. The fair value measurement was based on the pricing in the purchase and sale agreement. As significant inputs to the model are unobservable, the Company determined that the value determined for this property falls within Level 3 fair value reporting.

[2] During the three-month period ended June 30, 2016, the Company determined that the sale of a property located in Oakland, California, known as Oakland Lot B, was probable and classified it as held for sale in accordance with applicable accounting standards for long lived assets. As the fair value less anticipated costs to sell exceeded the carrying value of the property no impairment loss was recorded. The fair value measurement was based on pricing in the purchase and sale agreement. As the sales price is unobservable, the Company determined that the significant inputs used to value this property falls within Level 3 for fair value reporting.