Income per Common Unit of the Operating Partnership Unit Repurchase (Details) - Liberty Property Limited Partnership [Member] - 2017 Share Repurchase Program [Member] - Common Units [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 250
Stock Repurchased During Period, Shares	0	0