Income per Common Unit of the Operating Partnership - Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 12,123	$ 44,071	$ 56,953	$ 80,896
Income from discontinued operations	7,670	7,516	105,295	13,872
Net income available to common shareholders or unitholders	$ 19,614	$ 51,411	$ 159,795	$ 94,443
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares or Units Outstanding, Basic	147,274	146,688	147,184	146,602
Dilutive units for long-term compensation plans	1,059	820	920	753
Weighted Average Number of Shares or Units Outstanding, Diluted	148,333	147,508	148,104	147,355
Liberty Property Limited Partnership [Member]
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 12,529	$ 45,245	$ 58,542	$ 83,070
Less: Preferred unit distributions	(118)	(118)	(236)	(236)
Income from continuing operations available to common unitholders	12,411	45,127	58,306	82,834
Income from discontinued operations	7,670	7,516	105,295	13,872
Net income available to common shareholders or unitholders	$ 20,081	$ 52,643	$ 163,601	$ 96,706
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares or Units Outstanding, Basic	150,794	150,216	150,704	150,130
Dilutive units for long-term compensation plans	1,059	820	920	753
Weighted Average Number of Shares or Units Outstanding, Diluted	151,853	151,036	151,624	150,883
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Unit, Basic [Abstract]
Income from continuing operations	$ 0.08	$ 0.30	$ 0.39	$ 0.55
Income from discontinued operations	0.05	0.05	0.70	0.09
Income per common share or unit - basic	0.13	0.35	1.09	0.64
Earnings Per Unit, Diluted [Abstract]
Income from continuing operations	0.08	0.30	0.39	0.55
Income from discontinued operations	0.05	0.05	0.69	0.09
Income per common share or unit - diluted	$ 0.13	$ 0.35	$ 1.08	$ 0.64