Investment in Office Properties - Schedule of Unaudited Pro Forma Result of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
2015 Acquisitions
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues	$ 486,680	$ 489,312
Net loss attributable to common stockholders	$ 67,789	$ 45,886
Basic net income attributable to common stockholders (in dollars per share)	$ 0.61	$ 0.45
Diluted net income attributable to common stockholders (in dollars per share)	$ 0.61	$ 0.45
2014 Acquisitions
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues		$ 493,708	$ 370,980
Net loss attributable to common stockholders		$ 39,873	$ (18,471)
Basic net income attributable to common stockholders (in dollars per share)		$ 0.39	$ (0.28)
Diluted net income attributable to common stockholders (in dollars per share)		$ 0.37	$ (0.28)