Income per Common Unit of the Operating Partnership - Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income (Numerator) [Abstract]
Net income available to common shareholders	$ 59,539	$ 54,253	$ 153,982	$ 161,434
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	146,811	146,215	146,678	146,121
Dilutive units for long-term compensation plans	785	892	752	667
Weighted Average Number of Shares Outstanding, Diluted	147,596	147,107	147,430	146,788
Liberty Property Limited Partnership [Member]
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 61,084	$ 55,677	$ 158,026	$ 165,684
Less: Preferred unit distributions	(118)	(118)	(354)	(354)
Net income available to common shareholders	$ 60,966	$ 55,559	$ 157,672	$ 165,330
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	150,339	149,751	150,206	149,659
Dilutive units for long-term compensation plans	785	892	752	667
Weighted Average Number of Shares Outstanding, Diluted	151,124	150,643	150,958	150,326
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Unit, Basic [Abstract]
Income per common share - basic	$ 0.41	$ 0.37	$ 1.05	$ 1.10
Earnings Per Unit, Diluted [Abstract]
Income per common share - diluted	$ 0.40	$ 0.37	$ 1.04	$ 1.10