Non-controlling Interests - Schedule of Changes in Trust's Ownership Interest in Subsidiaries (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Trusts Ownership Interest In Subsidiaries [Abstract]
Net income attributable to Winthrop Realty Trust	$ 641	$ 13,746
Increase (decrease) in Winthrop Realty Trust paid in capital adjustments from transaction with non-controlling interests		52
Changes from net income attributable to Winthrop Realty Trust and transfers from non-controlling interest	$ 641	$ 13,798