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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest	$ 59,091	$ 43,713	$ 151,150	$ 91,051
Income from discontinued operations	41,273	106,430	103,315	218,887
Net income available to common shareholders	$ 100,364	$ 150,143	$ 254,465	$ 309,938
Weighted Average Units (Denominator) [Abstract]
Income from continuing operations net of noncontrolling interest - basic, weighted average shares (in shares)	150,140	147,324	148,532	147,241
Dilutive units for long-term compensation plans	839	947	851	919
Income from continuing operations net of noncontrolling interest - diluted, weighted average shares (in shares)	150,979	148,271	149,383	148,160
Liberty Property Limited Partnership
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest	$ 60,484	$ 44,865	$ 154,872	$ 93,557
Preferred unit distributions	(83)	(118)	(251)	(354)
Income from continuing operations available to common unitholders	60,401	44,747	154,621	93,203
Income from discontinued operations	42,189	108,974	105,719	224,119
Net income available to common shareholders	$ 102,590	$ 153,721	$ 260,340	$ 317,322
Weighted Average Units (Denominator) [Abstract]
Income from continuing operations net of noncontrolling interest - basic, weighted average shares (in shares)	153,646	150,844	152,045	150,761
Dilutive units for long-term compensation plans	839	947	851	919
Income from continuing operations net of noncontrolling interest - diluted, weighted average shares (in shares)	154,485	151,791	152,896	151,680
Liberty Property Limited Partnership | Common Units
Earnings Per Unit, Basic [Abstract]
Income from continuing operations (in usd per share)	$ 0.39	$ 0.30	$ 1.02	$ 0.62
Income from discontinued operations (in usd per share)	0.28	0.72	0.69	1.48
Income per common share or unit - basic (in usd per share)	0.67	1.02	1.71	2.10
Earnings Per Unit, Diluted [Abstract]
Income from continuing operations (in usd per share)	0.39	0.29	1.01	0.61
Income from discontinued operations (in usd per share)	0.27	0.72	0.69	1.48
Income per common share or unit - diluted (in usd per share)	$ 0.66	$ 1.01	$ 1.70	$ 2.09