Consolidated Statements of Operations (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Gain on property dispositions	$ 60,582	$ 6,857	$ 17,859
Liberty Property Limited Partnership [Member]
Gain on property dispositions	$ 60,582	$ 6,857	$ 17,859