Consolidated Statement of Equity (USD $) In Thousands	Total	Common Shares Of Beneficial Interest [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Distributions in Excess of Net Income [Member]	Common Shares Held in Treasury [Member]	Total Liberty Property Trust Shareholders' Equity [Member]	Noncontrolling interest operating partnership-Common [Member]	Noncontrolling interest operating partnership-Preferred [Member]	Noncontrolling interest-consolidated joint ventures [Member]	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member] General Partners Equity [Member]	Liberty Property Limited Partnership [Member] Noncontrolling interest operating partnership-Common [Member]	Liberty Property Limited Partnership [Member] Noncontrolling interest operating partnership-Preferred [Member]	Liberty Property Limited Partnership [Member] Noncontrolling interest-consolidated joint ventures [Member]
Beginning Balance at Dec. 31, 2011	$ 2,459,756	$ 117	$ 2,617,355	$ (429)	$ (461,498)	$ (51,951)	$ 2,103,594	$ 64,428	$ 287,959	$ 3,775	$ 2,459,756	$ 2,103,594	$ 64,428	$ 287,959	$ 3,775
Net proceeds from the issuance of common shares	16,197	1	16,196				16,197
Net income	39,602				37,089		37,089	1,207	1,306	0	39,602	37,089	1,207	1,306	0
Contributions from partners											20,507	20,507
Distributions to partners											(62,409)	(55,586)	(1,788)	(5,035)
Distributions	(62,409)				(55,586)		(55,586)	(1,788)	(5,035)
Noncash compensation	4,310		4,310				4,310
Foreign currency translation adjustment	2,317			2,244			2,244	73			2,317	2,244	73
Redemption of noncontrolling interests - common units	(124,733)								(124,733)		(124,733)			(124,733)
Preferred Stock Redemption Discount	3,729								3,729		3,729			3,729
Ending Balance at Mar. 31, 2012	$ 2,338,769	$ 118	$ 2,637,861	$ 1,815	$ (479,995)	$ (51,951)	$ 2,107,848	$ 63,920	$ 163,226	$ 3,775	$ 2,338,769	$ 2,107,848	$ 63,920	$ 163,226	$ 3,775