Consolidated Balance Sheets (Parentheticals) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Deferred financing and leasing costs, accumulated amortization	$ 180,608,000	$ 169,468,000
Limited Partners' common units outstanding	3,539,075	3,553,566
Common shares of beneficial interest, par value per share	$ 0.001	$ 0.001
Common shares of beneficial interest, shares authorized	283,987,000	283,987,000
Common shares of beneficial interest, shares issued	147,753,980	148,557,270
Common shares of beneficial interest, shares outstanding	147,753,980	148,557,270
Liberty Property Limited Partnership [Member]
Deferred financing and leasing costs, accumulated amortization	$ 180,608,000	$ 169,468,000
Limited Partners' common units outstanding	3,539,075	3,553,566
Common shares of beneficial interest, shares outstanding	147,753,980	148,557,270
Series I 2 [Member]
Noncontrolling interest - operating partnership, preferred units outstanding	301,483	301,483
Series I 2 [Member] | Liberty Property Limited Partnership [Member]
Noncontrolling interest - operating partnership, preferred units outstanding	301,483	301,483