CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Rental income	$ 275,048	$ 243,378
Expenses:
Operating expenses	109,659	97,236
Depreciation and amortization	66,523	58,019
General and administrative	17,266	11,536
Acquisition related costs	628	2,502
Total expenses	194,076	169,293
Operating income	80,972	74,085
Interest and other income	458	285
Interest expense (including net amortization of debt discounts, premiums and deferred financing fees of $629 and $746, respectively)	(52,344)	(49,106)
Loss on early extinguishment of debt	(60,027)	(67)
Equity in earnings of investees	4,262	2,958
Gain on sale of equity investment	66,293
Income from continuing operations before income tax expense	39,614	28,155
Income tax expense	(988)	(492)
Income from continuing operations	38,626	27,663
Discontinued operations:
Loss from discontinued operations	(1,912)	(3,089)
Loss on asset impairment from discontinued operations	(3,946)
Gain on sale of properties from discontinued operations	1,260
Income before gain on sale of properties	34,028	24,574
Gain on sale of properties	1,596
Net income	35,624	24,574
Net income attributable to noncontrolling interest in consolidated subsidiary	(9,957)	(894)
Net income attributable to CommonWealth REIT	25,667	23,680
Preferred distributions	(11,151)	(13,823)
Net income available for CommonWealth REIT common shareholders	14,516	9,857
Amounts attributable to CommonWealth REIT common shareholders:
Income from continuing operations	19,114	12,946
Loss from discontinued operations	(1,912)	(3,089)
Loss on asset impairment from discontinued operations	(3,946)
Gain on sale of properties from discontinued operations	1,260
Net income available for CommonWealth REIT common shareholders	$ 14,516	$ 9,857
Weighted average common shares outstanding - basic and diluted (in shares)	94,154	83,722
Basic and diluted earnings per common share attributable to CommonWealth REIT common shareholders:
Income from continuing operations (in dollars per share)	$ 0.20	$ 0.15
Loss from discontinued operations (in dollars per share)	$ (0.05)	$ (0.04)
Net income available for common shareholders (in dollars per share)	$ 0.15	$ 0.12