Summary of Significant Accounting Policies - Reconciliation of Earnings Attributable to Common Shares Outstanding for the Basic and Diluted EPS (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic
Income from continuing operations	$ 1,177	$ 2,562	$ 11,063	$ 9,609
Net loss attributable to non-controlling interest	629	473	1,424	1,374
Preferred dividend of Series D Preferred Shares	(2,786)	(2,787)	(5,573)	(3,712)
Dividend of restricted shares	(98)		(124)
Income (loss) from continuing operations applicable to Common Shares	(1,078)	248	6,800	7,271
Income from discontinued operations	6,568	323	9,633	628
Allocation of undistributed earnings to Restricted Shares			(10)
Net income attributable to Common Shares	5,490	571	16,423	7,899
Basic Weighted-Average Common Shares	33,037	33,064	33,032	33,058
Income (loss) from continuing operations	$ (0.03)	$ 0.01	$ 0.21	$ 0.22
Income from discontinued operations	$ 0.20	$ 0.01	$ 0.29	$ 0.02
Net income attributable to Winthrop Realty Trust	$ 0.17	$ 0.02	$ 0.50	$ 0.24
Diluted
Income (loss) from continuing operations	1,177	2,562	11,063	9,609
Net loss attributable to non-controlling interest	629	473	1,424	1,374
Preferred dividend of Series D Preferred Shares	(2,786)	(2,787)	(5,573)	(3,712)
Amount allocated to restricted shares	(98)		(124)
Income (loss) from continuing operations applicable to Common Shares	(1,078)	248	6,800	7,271
Income from discontinued operations	6,568	323	9,633	628
Allocation of undistributed earnings to Restricted Shares			(10)
Net income attributable to Common Shares	$ 5,490	$ 571	$ 16,423	$ 7,899
Basic Weighted-Average Common Shares	33,037	33,064	33,032	33,058
Stock options (1)			2
Restricted shares (2)			7
Diluted weighted-average Common Shares	33,037	33,064	33,041	33,058
Income (loss) from continuing operations	$ (0.03)	$ 0.01	$ 0.21	$ 0.22
Income from discontinued operations	$ 0.20	$ 0.01	$ 0.29	$ 0.02
Net income attributable to Winthrop Realty Trust	$ 0.17	$ 0.02	$ 0.50	$ 0.24