Limited Partners' Equity of the Operating Partnership Limited Partners' Equity of the Operating Partnership (Details) (USD $)			9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Liberty Property Limited Partnership [Member] Series B Preferred Stock [Member] percentage	Sep. 30, 2011 Series B Preferred Stock [Member] percentage	Sep. 30, 2011 Liberty Property Limited Partnership [Member] Series E Preferred Stock [Member] percentage	Sep. 30, 2011 Series E Preferred Stock [Member] percentage	Sep. 30, 2011 Liberty Property Limited Partnership [Member] Series F Preferred Stock [Member] percentage	Sep. 30, 2011 Series F Preferred Stock [Member] percentage	Sep. 30, 2011 Liberty Property Limited Partnership [Member] Series G Preferred Stock [Member] percentage	Sep. 30, 2011 Series G Preferred Stock [Member] percentage	Sep. 30, 2011 Liberty Property Limited Partnership [Member] Series H Preferred Stock [Member] percentage	Sep. 30, 2011 Series H Preferred Stock [Member] percentage	Sep. 30, 2011 Liberty Property Limited Partnership [Member]	Dec. 31, 2010 Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Limited Partners' Capital Account, Units Issued													3,808,746	3,928,733
Noncontrolling Interest in Operating Partnerships			$ 95,000,000	$ 95,000,000	$ 20,000,000	$ 20,000,000	$ 50,000,000	$ 50,000,000	$ 27,000,000	$ 27,000,000	$ 100,000,000	$ 100,000,000
Preferred Units, Outstanding	9,740,000	9,740,000	3,800,000	3,800,000	400,000	400,000	1,000,000	1,000,000	540,000	540,000	4,000,000	4,000,000	9,740,000	9,740,000
Redeemable Preferred Units Liquidation Preference			25	25	50	50	50	50	50	50	25	25
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount			7.45%	7.45%	7.00%	7.00%	6.65%	6.65%	6.70%	6.70%	7.40%	7.40%
preferred units redeemable date			Aug. 31, 2009	Aug. 31, 2009	Jun. 16, 2010	Jun. 16, 2010	Jun. 30, 2010	Jun. 30, 2010	Dec. 15, 2011	Dec. 15, 2011	Aug. 21, 2012	Aug. 21, 2012
Redeemable preferred units Exchangeable date			8/31/13 into Series B Cumulative Redeemable Preferred Shares of the Trust	8/31/13 into Series B Cumulative Redeemable Preferred Shares of the Trust	6/16/15 into Series E Cumulative Redeemable Preferred Shares of the Trust	6/16/15 into Series E Cumulative Redeemable Preferred Shares of the Trust	12/12/15 into Series F Cumulative Redeemable Preferred Shares of the Trust	12/12/15 into Series F Cumulative Redeemable Preferred Shares of the Trust	12/15/16 into Series G Cumulative Redeemable Preferred Shares of the Trust	12/15/16 into Series G Cumulative Redeemable Preferred Shares of the Trust	8/21/17 into Series H Cumulative Redeemable Preferred Shares of the Trust	8/21/17 into Series H Cumulative Redeemable Preferred Shares of the Trust
Noncontrolling Interest Operating Partnership Common Units Outstanding	3,808,746	3,928,733
market value of the outstanding common units	$ 110,900,000												$ 110,900,000