Consolidated Statement of Equity (USD $)	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, 2009	$ 2,483,169,000	$ 114,000	$ 2,509,704,000	$ 2,339,000	$ (337,911,000)	$ (51,951,000)	$ 2,122,295,000	$ 72,294,000	$ 287,959,000	$ 621,000	$ 2,483,169,000	$ 2,122,295,000	$ 72,294,000	$ 287,959,000	$ 621,000
Units Outstanding - Begining of Period at Dec. 31, 2009												4,011,354
Common shares, shares outstanding - Beginning of Period at Dec. 31, 2009		113,875,211
Contributions from partners											49,011,000	49,011,000
Distributions to partners											(244,421,000)	(215,868,000)	(7,541,000)	(21,012,000)	0
Net proceeds from the issuance of common shares	37,416,000	2,000	37,414,000	0	0	0	37,416,000	0	0	0
Net income	153,375,000	0	0	0	127,762,000	0	127,762,000	4,436,000	21,012,000	165,000	153,375,000	127,762,000	4,436,000	21,012,000	165,000
Redemption of limited partners common units for common shares												1,480,000	(1,480,000)
Distributions	(244,421,000)	0	0	0	(215,868,000)	0	(215,868,000)	(7,541,000)	(21,012,000)	0
Noncash compensation	11,595,000	0	11,595,000	0	0	0	11,595,000	0	0	0
Foreign currency translation adjustment	(2,582,000)	0	0	(2,494,000)	0	0	(2,494,000)	(88,000)	0	0	(2,582,000)	(2,494,000)	(88,000)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests, Common Units	0	0	1,480,000	0	0	0	1,480,000	(1,480,000)	0	0
Excess of preferred unit carrying amount over redemption											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
Number of Common Units [Roll Forward]
Redemption of noncontrolling interests - common units	(82,621)										(82,621)
Ending Balance at Dec. 31, 2010	2,438,552,000	116,000	2,560,193,000	(155,000)	(426,017,000)	(51,951,000)	2,082,186,000	67,621,000	287,959,000	786,000	2,438,552,000	2,082,186,000	67,621,000	287,959,000	786,000
Units Outstanding - End of Period at Dec. 31, 2010												3,928,733
Common shares, shares outstanding - End of Period at Dec. 31, 2010		115,530,608
Contributions from partners											55,103,000	55,103,000
Distributions to partners											(247,829,000)	(219,480,000)	(7,280,000)	(21,069,000)	0
Net proceeds from the issuance of common shares	44,548,000	1,000	44,547,000	0	0	0	44,548,000	0	0	0
Net income	210,710,000	0	0	0	183,999,000	0	183,999,000	6,153,000	21,069,000	(511,000)	210,710,000	183,999,000	6,153,000	21,069,000	(511,000)
Redemption of limited partners common units for common shares												2,060,000	(2,060,000)
Contributions	3,500,000	0	0	0	0	0	0	0	0	3,500,000
Distributions	(247,829,000)	0	0	0	(219,480,000)	0	(219,480,000)	(7,280,000)	(21,069,000)	0
Noncash compensation	10,555,000	0	10,555,000	0	0	0	10,555,000	0	0	0
Foreign currency translation adjustment	(280,000)	0	0	(274,000)	0	0	(274,000)	(6,000)	0	0	(280,000)	(274,000)	(6,000)
Partners' Capital, Other											3,500,000	0	0	0	3,500,000
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests, Common Units	0	0	2,060,000	0	0	0	2,060,000	(2,060,000)	0	0
Excess of preferred unit carrying amount over redemption											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
Number of Common Units [Roll Forward]
Redemption of noncontrolling interests - common units	(119,987)										(119,987)
Ending Balance at Dec. 31, 2011	2,459,756,000	117,000	2,617,355,000	(429,000)	(461,498,000)	(51,951,000)	2,103,594,000	64,428,000	287,959,000	3,775,000	2,459,756,000	2,103,594,000	64,428,000	287,959,000	3,775,000
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
Contributions from partners											68,767,000	68,767,000
Distributions to partners											(240,885,000)	(223,695,000)	(7,109,000)	(9,902,000)	(179,000)
Net proceeds from the issuance of common shares	58,710,000	2,000	58,708,000	0	0	0	58,710,000	0	0	0
Net income	147,751,000	0	0	0	137,436,000	0	137,436,000	4,378,000	6,212,000	(275,000)	147,751,000	137,436,000	4,378,000	6,212,000	(275,000)
Redemption of limited partners common units for common shares											0	1,581,000	(1,581,000)
Distributions	(240,885,000)	0	0	0	(223,695,000)	0	(223,695,000)	(7,109,000)	(9,902,000)	(179,000)
Noncash compensation	10,057,000	0	10,057,000	0	0	0	10,057,000	0	0	0
Foreign currency translation adjustment	3,436,000	0	0	3,329,000	0	0	3,329,000	107,000	0	0	3,436,000	3,329,000	107,000
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests, Common Units	0	0	1,581,000	0	0	0	1,581,000	(1,581,000)	0	0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests, Preferred Units	(224,694,000)	0	0	0	0	0	0	0	(224,694,000)	0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests											(224,694,000)			(224,694,000)
Excess of preferred unit carrying amount over redemption	3,689,000	0	0	0	0	0	0	0	3,689,000	0	3,689,000			3,689,000
Number of Common Shares [Roll Forward]
Stock Issued During Period, Shares, New Issues		2,273,528
Redemption of noncontrolling interests - common units	94,895											94,895
Number of Common Units [Roll Forward]
Redemption of noncontrolling interests - common units	(94,895)											(94,895)
Ending Balance at Dec. 31, 2012	$ 2,217,820,000	$ 119,000	$ 2,687,701,000	$ 2,900,000	$ (547,757,000)	$ (51,951,000)	$ 2,091,012,000	$ 60,223,000	$ 63,264,000	$ 3,321,000	$ 2,217,820,000	$ 2,091,012,000	$ 60,223,000	$ 63,264,000	$ 3,321,000
Units Outstanding - End of Period at Dec. 31, 2012	3,713,851											3,713,851
Common shares, shares outstanding - End of Period at Dec. 31, 2012	119,720,776	119,720,776									118,470,867