CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 27,886	$ 242,377	$ 453,393	$ 452,974
Other comprehensive income, net of tax:
Unrealized gain on marketable securities	0	0	0	342
Total comprehensive income	27,886	242,377	453,393	453,316
Comprehensive income attributable to the noncontrolling interest	(54)	(91)	(802)	(170)
Total comprehensive income attributable to Equity Commonwealth	$ 27,832	$ 242,286	$ 452,591	$ 453,146