Non-controlling Interests (Details) (USD $) In Thousands, 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
Schedule of changes in the Trust's ownership interest in the subsidiaries
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
Decrease in Winthrop Realty Trust paid in capital adjustments from non-controlling interests									(4,533)
Changes from net income attributable to Winthrop Realty Trust and transfers from non-controlling interests									$ 20,098	$ 10,933	$ 16,477