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]	Total Liberty Property Trust Shareholders' Equity [Member]	Noncontrolling interest operating partnership Common [Member]	Noncontrolling interest-consolidated joint ventures [Member]	Total Equity [Member]	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member] General Partners Equity [Member]	Liberty Property Limited Partnership [Member] Limited Partners' Equity - Common Units [Member]	Liberty Property Limited Partnership [Member] Noncontrolling interest-consolidated joint ventures [Member]	Liberty Property Limited Partnership [Member] Total Equity [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 139,664,000									$ 139,664,000
Other comprehensive loss - foreign currency translation	(5,189,000)									(5,189,000)
Other comprehensive loss - derivative instruments	(990,000)									(990,000)
Beginning Balance at Dec. 31, 2014	3,086,377,000	$ 149,000	$ 3,688,644,000	$ (6,252,000)	$ (654,869,000)	$ 3,027,672,000	$ 54,786,000	$ 3,919,000	$ 3,086,377,000	3,086,377,000	$ 3,027,672,000	$ 54,786,000	$ 3,919,000	$ 3,086,377,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from the issuance of common shares			38,195,000			38,195,000			38,195,000
Net income	162,085,000				157,797,000	157,797,000	3,763,000	171,000	161,731,000	162,085,000	157,797,000	3,763,000	171,000	161,731,000
Redemption of limited partners common units for common shares			224,000			224,000	(224,000)		0		224,000	(224,000)		0
Contributions from partners											49,595,000			49,595,000
Distributions					(212,019,000)	(212,019,000)	(5,173,000)	(171,000)	(217,363,000)
Distributions to partners											(212,019,000)	(5,173,000)	(171,000)	(217,363,000)
Share/Unit repurchase		(1,000)	(65,462,000)			(65,463,000)			(65,463,000)		(65,463,000)			(65,463,000)
Share-based compensation			11,400,000			11,400,000			11,400,000
Other comprehensive loss - foreign currency translation	(6,229,000)			(6,082,000)		(6,082,000)	(147,000)		(6,229,000)	(6,229,000)	(6,082,000)	(147,000)		(6,229,000)
Other comprehensive loss - derivative instruments	(1,539,000)			(1,503,000)		(1,503,000)	(36,000)		(1,539,000)	(1,539,000)	(1,503,000)	(36,000)		(1,539,000)
Ending Balance at Sep. 30, 2015	3,007,109,000	$ 148,000	$ 3,673,001,000	$ (13,837,000)	$ (709,091,000)	$ 2,950,221,000	$ 52,969,000	$ 3,919,000	$ 3,007,109,000	3,007,109,000	$ 2,950,221,000	$ 52,969,000	$ 3,919,000	$ 3,007,109,000
Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance at Dec. 31, 2014	7,537,000									7,537,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (Mezzanine)	354,000									354,000
Distributions (Mezzanine)	(354,000)									(354,000)
Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance at Sep. 30, 2015	$ 7,537,000									$ 7,537,000