CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (16,429)	$ 452,093	$ 492,866
Other comprehensive income, net of tax:
Unrealized gain, net on marketable securities	0	0	342
Total comprehensive (loss) income	(16,429)	452,093	493,208
Comprehensive loss (income) attributable to noncontrolling interest	33	(799)	(186)
Total comprehensive (loss) income attributable to Equity Commonwealth	$ (16,396)	$ 451,294	$ 493,022