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, 2012	$ 2,217,820	$ 119	$ 2,687,701	$ 2,900	$ (547,757)	$ (51,951)	$ 2,091,012	$ 60,223	$ 63,264	$ 3,321	$ 2,217,820	$ 2,091,012	$ 60,223	$ 63,264	$ 3,321
Net proceeds from the issuance of common shares	44,927	2	44,925				44,927
Net income	74,656				71,239		71,239	2,206	1,211	0	74,656	71,239	2,206	1,211	0
Contributions from partners											49,372	49,372
Distributions to partners											(60,007)	(56,953)	(1,843)	(1,211)
Distributions	(60,007)				(56,953)		(56,953)	(1,843)	(1,211)
Share-based compensation	4,445		4,445				4,445
Foreign currency translation adjustment	(4,851)			(4,705)			(4,705)	(146)			(4,851)	(4,705)	(146)
Ending Balance at Mar. 31, 2013	$ 2,276,990	$ 121	$ 2,737,071	$ (1,805)	$ (533,471)	$ (51,951)	$ 2,149,965	$ 60,440	$ 63,264	$ 3,321	$ 2,276,990	$ 2,149,965	$ 60,440	$ 63,264	$ 3,321