Summary of Significant Accounting Policies (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Basic
Income from continuing operations									$ 24,451	$ 11,092	$ 19,106
Net (income) loss attributable to non-controlling interest									247	(814)	(888)
Preferred dividend of Series C Preferred Shares										(585)	(288)
Preferred dividend of Series D Preferred Shares									(9,285)	(339)
Income from continuing operations applicable to Common Shares									15,413	9,354	17,930
Income (loss) from discontinued operations									(67)	655	(1,741)
Net income attributable to Common Shares	(4,875)	12,322	571	7,328	(10,587)	9,787	3,670	7,139	15,346	10,009	16,189
Basic weighted-average Common Shares									33,062	31,428	22,566
Income from continuing operations	$ (0.15)	$ 0.37	$ 0.02	$ 0.22	$ (0.32)	$ 0.30	$ 0.11	$ 0.26	$ 0.46	$ 0.30	$ 0.80
Income (loss) from discontinued operations										$ 0.02	$ (0.08)
Net income attributable to Winthrop Realty Trust									$ 0.46	$ 0.32	$ 0.72
Diluted
Income from continuing operations									24,451	11,092	19,106
Net (income) loss attributable to non-controlling interest									247	(814)	(888)
Preferred dividend of Series C Preferred Shares										(585)	(288)
Preferred dividend of Series D Preferred Shares									(9,285)	(339)
Income from continuing operations applicable to Common Shares									15,413	9,354	17,930
Income (loss) from discontinued operations									(67)	655	(1,741)
Net income attributable to Common Shares	$ (4,875)	$ 12,322	$ 571	$ 7,328	$ (10,587)	$ 9,787	$ 3,670	$ 7,139	$ 15,346	$ 10,009	$ 16,189
Basic weighted-average Common Shares									33,062	31,428	22,566
Stock options (3)											2
Diluted Weighted-Average Common Shares									33,062	31,428	22,568
Income from continuing operations	$ (0.15)	$ 0.37	$ 0.02	$ 0.22	$ (0.32)	$ 0.30	$ 0.11	$ 0.26	$ 0.46	$ 0.30	$ 0.80
Income (loss) from discontinued operations										$ 0.02	$ (0.08)
Net income attributable to Winthrop Realty Trust									$ 0.46	$ 0.32	$ 0.72
Series B-1 [Member]
Diluted
Preferred Shares
Series C [Member]
Diluted
Preferred Shares