Liability for Estimated Costs in Excess of Estimated Receipts During Liquidation - Summary of Accrued Revenues and Expenses Expected to Incur During Liquidation (Detail) - Liquidation Value [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Liquidation Basis Of Accounting [Line Items]
Rents and reimbursements	$ 14,369
Interest and dividends	1,036
Property operating expenses	(4,803)
Interest expense	(4,911)
General and administrative expenses	(24,866)
Capital expenditures	(1,159)
Sales costs	(2,852)
Liability for estimated costs in excess of estimated receipts during liquidation	$ (23,186)
Winthrop Realty Trust [Member]
Liquidation Basis Of Accounting [Line Items]
Rents and reimbursements		$ 29,636
Interest and dividends		3,646
Property operating expenses		(10,756)
Interest expense		(7,546)
General and administrative expenses		(34,264)
Capital expenditures		(4,027)
Sales costs		(5,986)
Liability for estimated costs in excess of estimated receipts during liquidation		$ (29,297)