Quarterly Results of Operations (Unaudited) (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
Selected quarterly financial information
Revenues	$ 19,255	$ 17,057	$ 18,588	$ 17,598	$ 16,282	$ 15,873	$ 15,879	$ 20,213	$ 72,498	$ 68,247	$ 53,402
Net income (loss) attributable to Winthrop Realty Trust	(2,088)	15,108	3,358	8,253	(9,839)	9,846	3,728	7,198	24,631	10,933	16,477
Net income (loss) applicable 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
Net income (loss) applicable to Common Shares, basic	$ (0.15)	$ 0.37	$ 0.02	$ 0.22	$ (0.32)	$ 0.30	$ 0.11	$ 0.26	$ 0.46	$ 0.30	$ 0.80
Net income (loss) applicable to Common Shares, diluted	$ (0.15)	$ 0.37	$ 0.02	$ 0.22	$ (0.32)	$ 0.30	$ 0.11	$ 0.26	$ 0.46	$ 0.30	$ 0.80