CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 23,822	$ 46,402
Other comprehensive (loss) income, net of tax:
Unrealized (loss) gain on derivative instruments	(153)	673
Unrealized loss on marketable securities	(641)	0
Total comprehensive income	23,028	47,075
Comprehensive income attributable to the noncontrolling interest	(8)	0
Total comprehensive income attributable to Equity Commonwealth	$ 23,020	$ 47,075