Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2011	Dec. 31, 2010
Accumulated amortization on deferred financing and leasing costs	$ 125,626,000	$ 115,124,000
Common shares, par value	$ 0.001	$ 0.001
Common shares, shares authorized	183,987,000	183,987,000
Common shares, shares issued	116,955,528	115,530,608
Common shares, shares outstanding	116,955,528	115,530,608
Treasury stock, shares	1,249,909	1,249,909
Noncontrolling Interest Operating Partnership Common Units Outstanding	3,808,746	3,928,733
Preferred stock, units outstanding	9,740,000	9,740,000
Liberty Property Limited Partnership [Member]
Accumulated amortization on deferred financing and leasing costs	$ 125,626,000	$ 115,124,000
Common shares, shares outstanding	115,705,619	114,280,699
Treasury stock, shares	1,249,909	1,249,909
Preferred stock, units outstanding	9,740,000	9,740,000
Limited partners capital account, units issued	3,808,746	3,928,733