Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Accumulated amortization on deferred financing and leasing costs	$ 120,290	$ 115,118
Common shares, par value	$ 0.001	$ 0.001
Common shares, shares authorized	183,987,000	183,987,000
Common shares, shares issued	116,575,289	115,530,608
Common shares, shares outstanding	116,575,289	115,530,608
Treasury stock, shares	1,249,909	1,249,909
Noncontrolling interest - operating partnership, common units outstanding	3,902,065	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	$ 120,290	$ 115,118
Common shares, shares outstanding	116,575,289	115,530,608
Preferred stock, units outstanding	9,740,000	9,740,000
Limited partners' capital account, units issued	3,902,065	3,928,733