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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 91,331	$ 34,293	$ 157,797	$ 88,430
Income from discontinued operations	0	133	0	48,276
Net income available to common shareholders	$ 91,331	$ 34,423	$ 157,797	$ 135,572
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	148,582	147,422	148,594	146,987
Dilutive units for long-term compensation plans	594	666	626	674
Weighted Average Number of Shares Outstanding, Diluted	149,176	148,088	149,220	147,661
Liberty Property Limited Partnership [Member]
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 93,637	$ 35,234	$ 161,914	$ 90,914
Less: Preferred unit distributions	(118)	(118)	(354)	(354)
Income from Continuing Operations available to Common Unitholders	93,519	35,116	161,560	90,560
Income from discontinued operations	0	133	0	48,276
Net income available to common shareholders	$ 93,519	$ 35,249	$ 161,560	$ 138,836
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	152,121	150,976	152,134	150,541
Dilutive units for long-term compensation plans	594	666	626	674
Weighted Average Number of Shares Outstanding, Diluted	152,715	151,642	152,760	151,215
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Unit, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.61	$ 0.23	$ 1.06	$ 0.60
Income from Discontinued Operations, Per Basic Share	0.00	0.00	0.00	0.32
Income per common share - basic	0.61	0.23	1.06	0.92
Earnings Per Unit, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	0.61	0.23	1.06	0.60
Income from Discontinued Operations, Per Diluted Share	0.00	0.00	0.00	0.32
Income per common share - diluted	$ 0.61	$ 0.23	$ 1.06	$ 0.92