Federal and State Income Taxes (Details 2) (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
Summary of GAAP net income attributable to Trust to taxable income
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
Book/Tax differences from depreciation and amortization expense									5,297	4,588	189
Book/Tax differences of accretion of discount									(8,333)	(13,401)	(8,782)
Book/Tax differences of unrealized gains									(6,923)	(2,788)	(10,080)
Book/Tax differences on gains/losses from capital transactions									(1,876)	(5,842)	1,655
Book/Tax differences on Preferred Shares										1,428	1,563
Book/Tax differences for impairment losses									3,260	7,600	2,720
Book/Tax differences on investments in unconsolidated joint ventures									4,131	31,634	15,661
Other book/tax differences, net									(8,781)	(766)	(134)
Book/Tax differences on dividend income									(452)	(371)	93
Book/Tax differences of market discount									14,065	13,250
Taxable income									$ 25,019	$ 46,265	$ 19,362