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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 35,513	$ 28,961	$ 66,464	$ 54,137
Discontinued operations	0	295	0	48,143
Net income available to common shareholders	$ 35,513	$ 29,249	$ 66,464	$ 101,149
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	148,778	147,012	148,574	146,749
Dilutive units for long-term compensation plans	676	762	673	695
Weighted Average Number of Shares Outstanding, Diluted	149,454	147,774	149,247	147,444
Liberty Property Limited Partnership [Member]
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 36,471	$ 29,775	$ 68,275	$ 55,680
Less: Preferred unit distributions	(118)	(118)	(236)	(236)
Income from Continuing Operations available to Common Unitholders	36,353	29,657	68,039	55,444
Discontinued operations	0	295	0	48,143
Net income available to common shareholders	$ 36,353	$ 29,952	$ 68,039	$ 103,587
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	152,317	150,563	152,114	150,304
Dilutive units for long-term compensation plans	676	762	673	695
Weighted Average Number of Shares Outstanding, Diluted	152,993	151,325	152,787	150,999
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.24	$ 0.20	$ 0.45	$ 0.37
Income from Discontinued Operations, Per Basic Share	0.00	0.00	0.00	0.32
Income per common share - basic	0.24	0.20	0.45	0.69
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	0.24	0.20	0.45	0.37
Income from Discontinued Operations, Per Diluted Share	0.00	0.00	0.00	0.32
Income per common share - diluted	$ 0.24	$ 0.20	$ 0.45	$ 0.69