Other Comprehensive Income of the Operating Partnership (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Comprehensive Income [Line Items]
Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, before Tax	$ (280,000)	$ (2,582,000)	$ 7,999,000
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	210,400,000	150,800,000	87,000,000
Liberty Property Limited Partnership [Member]
Other Comprehensive Income [Line Items]
Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, before Tax	(280,000)	(2,582,000)	7,999,000
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 210,400,000	$ 150,800,000	$ 87,000,000