Income per Common Unit of the Operating Partnership (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income
Income from continuing operations net of noncontrolling interest									$ 263,805	$ 345,108	$ 229,164
Income from discontinued operations	$ 17,361	$ (2,809)	$ 2,308	$ 2,119	$ 3,253	$ 4,059	$ 2,242	$ 2,437	18,979	11,991	10,565
Income available to common shareholders									$ 282,340	$ 356,817	$ 239,483
Weighted Average Shares
Income from continuing operations net of noncontrolling interest - basic (shares)									146,742	146,204	148,243
Dilutive shares/units for long-term compensation plans (shares)									799	685	600
Income from continuing operations net of noncontrolling interest - diluted (shares)									147,541	146,889	148,843
Per Share/Unit
Net income available to common shareholders - basic (USD per share/unit)	$ 0.87	$ 0.41	$ 0.35	$ 0.29	$ 1.33	$ 0.37	$ 0.34	$ 0.39
Per Share
Income per common share - diluted (USD per share/unit)	$ 0.87	$ 0.40	$ 0.35	$ 0.29	$ 1.33	$ 0.37	$ 0.34	$ 0.39
Liberty Property Limited Partnership [Member]
Income
Income from continuing operations net of noncontrolling interest									$ 270,585	$ 353,896	$ 235,110
Less: Preferred unit distributions									(472)	(472)	(472)
Income from continuing operations available to common unitholders									270,113	353,424	234,638
Income from discontinued operations									18,979	11,991	10,565
Income available to common shareholders									$ 289,092	$ 365,415	$ 245,203
Weighted Average Shares
Income from continuing operations net of noncontrolling interest - basic (shares)									150,270	149,740	151,783
Dilutive shares/units for long-term compensation plans (shares)									799	685	600
Income from continuing operations net of noncontrolling interest - diluted (shares)									151,069	150,425	152,383
Liberty Property Limited Partnership [Member] | Common units [Member]
Per Share/Unit
Income from continuing operations net of noncontrolling interest - basic (USD per share/unit)									$ 1.79	$ 2.36	$ 1.55
Discontinued operations net of noncontrolling interest - basic (USD per share/unit)									0.13	0.08	0.07
Net income available to common shareholders - basic (USD per share/unit)									1.92	2.44	1.62
Per Share
Income from continuing operations net of noncontrolling interest - diluted (USD per share/unit)									1.78	2.35	1.54
Discontinued operations net of noncontrolling interest - diluted (USD per share/unit)									0.13	0.08	0.07
Income per common share - diluted (USD per share/unit)									$ 1.91	$ 2.43	$ 1.61