Income per Common Unit of the Operating Partnership Income per Common Unit of the Operations Partnership, Dilutive Options (Details) (Liberty Property Limited Partnership [Member], Stock Option [Member], Common Units [Member])	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Liberty Property Limited Partnership [Member] | Stock Option [Member] | Common Units [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	0	43,000	504,000