Consolidated Statement of Equity (USD $) In Thousands, except Share data, unless otherwise specified	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, 2008	$ 2,326,506	$ 101	$ 2,201,728	$ (5,378)	$ (185,721)	$ (51,951)	$ 1,958,779	$ 78,638	$ 287,959	$ 1,130	$ 1,945,516	$ 1,944,386	$ 0	$ 0	$ 1,130
Units Outstanding - Begining of Period at Dec. 31, 2008												4,074,967
Common shares, shares outstanding - Beginning of Period at Dec. 31, 2008		100,034,404
Transfer of noncontrolling interests to permanent equity											380,990	0	93,031	287,959	0
Contributions from partners											306,763	306,763
Distributions to partners											(237,091)	(208,566)	(7,513)	(21,012)
Net proceeds from the issuance of common shares	293,858	13	293,845	0	0	0	293,858	0	0	0
Net income	78,992	0	0	0	56,376	0	56,376	2,113	21,012	(509)	78,992	56,376	2,113	21,012	(509)
Redemption of limited partners common units for common shares												15,619	(15,619)
Distributions	(237,091)	0	0	0	(208,566)	0	(208,566)	(7,513)	(21,012)	0
Noncash compensation	12,905	0	12,905	0	0	0	12,905	0	0	0
Foreign currency translation adjustment	7,999	0	0	7,717	0	0	7,717	282	0	0	7,999	7,717	282
Redemption of noncontrolling interests - common units	0	0	1,226	0	0	0	1,226	(1,226)	0	0
Number of Common Shares [Roll Forward]
Stock Issued During Period, Shares, New Issues		13,777,194
Redemption of noncontrolling interests - common units	63,613	63,613									63,613	63,613
Number of Common Units [Roll Forward]
Redemption of limited partners common units for common shares	(63,613)	(63,613)									(63,613)	(63,613)
Ending Balance at Dec. 31, 2009	2,483,169	114	2,509,704	2,339	(337,911)	(51,951)	2,122,295	72,294	287,959	621	2,483,169	2,122,295	72,294	287,959	621
Units Outstanding - End of Period at Dec. 31, 2009												4,011,354
Common shares, shares outstanding - End of Period at Dec. 31, 2009		113,875,211
Contributions from partners											49,011	49,011
Distributions to partners											(244,421)	(215,868)	(7,541)	(21,012)
Net proceeds from the issuance of common shares	37,416	2	37,414	0	0	0	37,416	0	0	0
Net income	153,375	0	0	0	127,762	0	127,762	4,436	21,012	165	153,375	127,762	4,436	21,012	165
Redemption of limited partners common units for common shares												1,480	(1,480)
Distributions	(244,421)	0	0	0	(215,868)	0	215,868	(7,541)	(21,012)	0
Noncash compensation	11,595	0	11,595	0	0	0	11,595	0	0	0
Foreign currency translation adjustment	(2,582)	0	0	(2,494)	0	0	(2,494)	(88)	0	0	(2,582)	(2,494)	(88)
Redemption of noncontrolling interests - common units	0	0	1,480	0	0	0	1,480	(1,480)	0	0
Number of Common Shares [Roll Forward]
Stock Issued During Period, Shares, New Issues		1,572,776
Redemption of noncontrolling interests - common units	82,621	82,621									82,621	82,621
Number of Common Units [Roll Forward]
Redemption of limited partners common units for common shares	(82,621)	(82,621)									(82,621)	(82,621)
Ending Balance at Dec. 31, 2010	2,438,552	116	2,560,193	(155)	(426,017)	(51,951)	2,082,186	67,621	287,959	786	2,438,552	2,082,186	67,621	287,959	786
Units Outstanding - End of Period at Dec. 31, 2010	3,928,733											3,928,733
Common shares, shares outstanding - End of Period at Dec. 31, 2010	115,530,608	115,530,608									114,280,699
Contributions from partners											58,603	55,103			3,500
Distributions to partners											(247,829)	(219,480)	(7,280)	(21,069)
Net proceeds from the issuance of common shares	44,548	1	44,547	0	0	0	44,548	0	0	0
Net income	210,710	0	0	0	(183,999)	0	183,999	6,153	21,069	(511)	210,710	183,999	6,153	21,069	(511)
Redemption of limited partners common units for common shares												2,060	(2,060)
Contributions	3,500	0	0	0	0	0	0	0	0	3,500
Distributions	(247,829)	0	0	0	(219,480)	0	(219,480)	7,280	21,069	0
Noncash compensation	10,555	0	10,555	0	0	0	10,555	0	0	0
Foreign currency translation adjustment	(280)	0	0	(274)	0	0	(274)	(6)	0	0	(280)	(274)	(6)
Redemption of noncontrolling interests - common units	0	0	(2,060)	0	0	0	2,060	2,060	0	0
Number of Common Shares [Roll Forward]
Stock Issued During Period, Shares, New Issues		1,701,758
Redemption of noncontrolling interests - common units	119,987	119,987									119,987	119,987
Number of Common Units [Roll Forward]
Redemption of limited partners common units for common shares	(119,987)	(119,987)									(119,987)	(119,987)
Ending 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
Units Outstanding - End of Period at Dec. 31, 2011	3,808,746											3,808,746
Common shares, shares outstanding - End of Period at Dec. 31, 2011	117,352,353	117,352,353									116,102,444