Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member] Noncontrolling Interest-Consolidated Joint Ventures [Member]	Liberty Property Limited Partnership [Member] General Partner [Member]	Liberty Property Limited Partnership [Member] Limited Partner [Member]	Common shares [Member]	Common units [Member] Liberty Property Limited Partnership [Member] General Partner [Member]	Common units [Member] Liberty Property Limited Partnership [Member] Limited Partner [Member]	Common Shares Of Beneficial Interest [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Distributions in Excess of Net Income [Member]	Total Liberty Property Trust Shareholders' Equity [Member]	Noncontrolling Interest- Operating Partnership - Common	Noncontrolling Interest-Consolidated Joint Ventures [Member]
Beginning Balance at Dec. 31, 2014	$ 3,106,312	$ 3,106,312	$ 3,919	$ 3,046,961	$ 55,432				$ 149	$ 3,688,644	$ (9,784)	$ (632,048)	$ 3,046,961	$ 55,432	$ 3,919
Common shares outstanding - Beginning Balance (shares) at Dec. 31, 2014						148,557,270
General Partner's units outstanding - Beginning Balance (shares) at Dec. 31, 2014							148,557,270
Limited Partners' units outstanding - Beginning Balance (shares) at Dec. 31, 2014								3,553,566
Increase (Decrease) in Stockholders' Equity
Net proceeds from the issuance of common shares	38,797									38,797			38,797
Net proceeds from the issuance of common shares (shares)						1,328,017
Net income	245,452	245,452	249	239,483	5,720							239,483	239,483	5,720	249
Distributions	(289,240)											(282,123)	(282,123)	(6,868)	(249)
Share-based compensation	13,763									13,763			13,763
Contributions from partners		52,560		52,560
Contributions from partners (shares)							1,328,017
Distributions to partners		(289,240)	(249)	(282,123)	(6,868)
Other comprehensive income (loss) - foreign currency translation	(12,540)	(12,540)		(12,245)	(295)						(12,245)		(12,245)	(295)
Other comprehensive (loss) income - derivative instruments	(488)	(488)		(477)	(11)						(477)		(477)	(11)
Redemption of noncontrolling interests – common units										224			224	(224)
Redemption of noncontrolling interests – common units (shares)						14,491	14,491
Redemption of limited partners common units for common shares				224	(224)
Redemption of limited partners common units for common shares (shares)								(14,491)
Share repurchase	(71,802)	(71,802)		(71,802)					(1)	(71,801)			(71,802)
Share repurchase (shares)						(2,321,794)	(2,321,794)
Common shares outstanding - Ending Balance (shares) at Dec. 31, 2015						147,577,984
Limited Partners' units outstanding - Ending Balance (shares) at Dec. 31, 2015								3,539,075
General Partner's units outstanding - Ending Balance (shares) at Dec. 31, 2015							147,577,984
Ending Balance at Dec. 31, 2015	3,030,254	3,030,254	3,919	2,972,581	53,754				148	3,669,627	(22,506)	(674,688)	2,972,581	53,754	3,919
Noncontrolling interest - operating partnership (mezzanine) - Beginning of Period at Dec. 31, 2014	7,537	7,537
Increase (Decrease) in Limited Partners' Equity
Temporary Equity, Net Income	472	472
Temporary Equity, Distributions	(472)	(472)
Noncontrolling interest - operating partnership (mezzanine) - End of Period at Dec. 31, 2015	7,537	7,537
Increase (Decrease) in Stockholders' Equity
Net proceeds from the issuance of common shares	13,029									13,029			13,029
Net proceeds from the issuance of common shares (shares)						802,834
Net income	365,673	365,673	258	356,817	8,598							356,817	356,817	8,598	258
Distributions	(285,802)											(278,764)	(278,764)	(6,780)	(258)
Share-based compensation	15,699									15,699			15,699
Contributions from partners		28,728		28,728
Contributions from partners (shares)							802,834
Distributions to partners		(285,802)	(258)	(278,764)	(6,780)
Other comprehensive income (loss) - foreign currency translation	(34,744)	(34,744)		(33,925)	(819)						(33,925)		(33,925)	(819)
Other comprehensive (loss) income - derivative instruments	410	410		400	10						400		400	10
Acquisition of noncontrolling interests	(700)	(700)	982	(1,682)						(1,682)			(1,682)		982
Redemption of noncontrolling interests – common units										132			132	(132)
Redemption of noncontrolling interests – common units (shares)						9,044	9,044
Redemption of limited partners common units for common shares				132	(132)
Redemption of limited partners common units for common shares (shares)								(9,044)
Share repurchase	$ (40,896)	$ (40,896)		(40,896)					(1)	(40,895)			(40,896)
Share repurchase (shares)						(1,396,844)	(1,396,844)
Common shares outstanding - Ending Balance (shares) at Dec. 31, 2016	146,993,018	146,993,018				146,993,018
Limited Partners' units outstanding - Ending Balance (shares) at Dec. 31, 2016		3,530,031						3,530,031
General Partner's units outstanding - Ending Balance (shares) at Dec. 31, 2016							146,993,018
Ending Balance at Dec. 31, 2016	$ 3,062,923	$ 3,062,923	4,901	3,003,391	54,631				147	3,655,910	(56,031)	(596,635)	3,003,391	54,631	4,901
Increase (Decrease) in Limited Partners' Equity
Temporary Equity, Net Income	472	472
Temporary Equity, Distributions	(472)	(472)
Noncontrolling interest - operating partnership (mezzanine) - End of Period at Dec. 31, 2016	7,537	7,537
Increase (Decrease) in Stockholders' Equity
Net proceeds from the issuance of common shares	8,808									8,808			8,808
Net proceeds from the issuance of common shares (shares)						447,847
Net income	289,573	289,573	481	282,340	6,752							282,340	282,340	6,752	481
Distributions	(241,717)											(235,675)	(235,675)	(5,509)	(533)
Share-based compensation	10,108									10,108			10,108
Contributions from partners		18,916		18,916
Contributions from partners (shares)							447,847
Distributions to partners		(241,717)	(533)	(235,675)	(5,509)
Other comprehensive income (loss) - foreign currency translation	18,066	18,066		17,643	423						17,643		17,643	423
Other comprehensive (loss) income - derivative instruments	$ 605	$ 605		591	14						591		591	14
Redemption of noncontrolling interests – common units										152			152	(152)
Redemption of noncontrolling interests – common units (shares)						9,826	9,826
Redemption of limited partners common units for common shares				152	(152)
Redemption of limited partners common units for common shares (shares)								(9,826)
Common shares outstanding - Ending Balance (shares) at Dec. 31, 2017	147,450,691	147,450,691				147,450,691
Limited Partners' units outstanding - Ending Balance (shares) at Dec. 31, 2017		3,520,205						3,520,205
General Partner's units outstanding - Ending Balance (shares) at Dec. 31, 2017							147,450,691
Ending Balance at Dec. 31, 2017	$ 3,148,366	$ 3,148,366	$ 4,849	$ 3,087,358	$ 56,159				$ 147	$ 3,674,978	$ (37,797)	$ (549,970)	$ 3,087,358	$ 56,159	$ 4,849
Increase (Decrease) in Limited Partners' Equity
Temporary Equity, Net Income	472	472
Temporary Equity, Distributions	(472)	(472)
Noncontrolling interest - operating partnership (mezzanine) - End of Period at Dec. 31, 2017	$ 7,537	$ 7,537