Consolidated Statements of Operations (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net gain on property dispositions included in discontinued operation	$ 1,064	$ 470
Liberty Property Limited Partnership [Member]
Net gain on property dispositions included in discontinued operation	$ 1,064	$ 470