Income per Common Unit of the Operating Partnership, Diluted (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 30,951	$ 25,179
Discontinued operations	0	47,848
Net income available to common shareholders	30,951	71,900
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	148,315	146,425
Dilutive units for long-term compensation plans	716	670
Weighted Average Number of Shares Outstanding, Diluted	149,031	147,095
Liberty Property Limited Partnership [Member]
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	31,804	25,905
Less: Preferred unit distributions	(118)	(118)
Income from Continuing Operations available to Common Unitholders	31,686	25,787
Discontinued operations	0	47,848
Net income available to common shareholders	$ 31,686	$ 73,635
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	151,856	149,981
Dilutive units for long-term compensation plans	716	670
Weighted Average Number of Shares Outstanding, Diluted	152,572	150,651
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.21	$ 0.17
Income from Discontinued Operations, Per Basic Share	$ 0.00	$ 0.32
Income per common share - basic	$ 0.21	$ 0.49
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	$ 0.21	$ 0.17
Income from Discontinued Operations, Per Diluted Share	$ 0.00	$ 0.32
Income per common share - diluted	$ 0.21	$ 0.49