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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest	$ 52,764	$ 7,308	$ 92,000	$ 47,447
Income from discontinued operations	47,005	12,306	62,100	112,348
Net income available to common shareholders	$ 99,769	$ 19,614	$ 154,100	$ 159,795
Weighted Average Units (Denominator) [Abstract]
Income from continuing operations net of noncontrolling interest - basic, weighted average shares (in shares)	147,805	147,274	147,706	147,184
Dilutive units for long-term compensation plans	863	1,059	900	920
Income from continuing operations net of noncontrolling interest - diluted, weighted average shares (in shares)	148,668	148,333	148,606	148,104
Earnings Per Unit, Diluted [Abstract]
Document Period End Date			Jun. 30, 2019
Liberty Property Limited Partnership
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest	$ 54,093	$ 7,597	$ 94,338	$ 48,804
Preferred unit distributions	(84)	(118)	(168)	(236)
Income from continuing operations available to common unitholders	54,009	7,479	94,170	48,568
Income from discontinued operations	48,119	12,602	63,579	115,033
Net income available to common shareholders	$ 102,128	$ 20,081	$ 157,749	$ 163,601
Weighted Average Units (Denominator) [Abstract]
Income from continuing operations net of noncontrolling interest - basic, weighted average shares (in shares)	151,319	150,794	151,223	150,704
Dilutive units for long-term compensation plans	863	1,059	900	920
Income from continuing operations net of noncontrolling interest - diluted, weighted average shares (in shares)	152,182	151,853	152,123	151,624
Liberty Property Limited Partnership | Common Units
Earnings Per Unit, Basic [Abstract]
Income from continuing operations (in usd per share)	$ 0.36	$ 0.05	$ 0.62	$ 0.33
Income from discontinued operations (in usd per share)	0.32	0.08	0.42	0.76
Income per common share or unit - basic (in usd per share)	0.68	0.13	1.04	1.09
Earnings Per Unit, Diluted [Abstract]
Income from continuing operations (in usd per share)	0.35	0.05	0.62	0.32
Income from discontinued operations (in usd per share)	0.32	0.08	0.42	0.76
Income per common share or unit - diluted (in usd per share)	$ 0.67	$ 0.13	$ 1.04	$ 1.08