CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental income	$ 270,320	$ 409,071	$ 570,382
Tenant reimbursements and other income	70,251	91,609	144,509
Total revenues	340,571	500,680	714,891
Expenses:
Operating expenses	141,425	200,706	324,948
Depreciation and amortization	90,708	131,806	194,001
General and administrative	47,760	50,256	57,457
Loss on asset impairment	19,714	58,476	17,162
Total expenses	299,607	441,244	593,568
Operating income	40,964	59,436	121,323
Interest and other income	26,380	10,331	5,989
Interest expense (including net amortization of debt discounts, premiums and deferred financing fees of $3,135, $3,725, and $1,028, respectively)	(52,183)	(84,329)	(107,316)
(Loss) gain on early extinguishment of debt	(493)	(2,680)	6,661
Foreign currency exchange loss	0	(5)	(8,857)
Gain on sale of properties, net	15,498	250,886	84,421
Income before income taxes	30,166	233,639	102,221
Income tax expense	(500)	(745)	(2,364)
Net income	29,666	232,894	99,857
Net income attributable to noncontrolling interest	(10)	0	0
Net income attributable to Equity Commonwealth	29,656	232,894	99,857
Preferred distributions	(7,988)	(17,956)	(27,924)
Excess fair value of consideration paid over carrying value of preferred shares	0	(9,609)	0
Net income attributable to Equity Commonwealth common shareholders	$ 21,668	$ 205,329	$ 71,933
Weighted average common shares outstanding — basic (in shares)	124,125	125,474	128,621
Weighted average common shares outstanding — diluted (in shares)	125,129	126,768	129,437
Earnings per common share attributable to Equity Commonwealth common shareholders:
Basic (in dollars per share)	$ 0.17	$ 1.64	$ 0.56
Diluted (in dollars per share)	$ 0.17	$ 1.62	$ 0.56