Limited Partners' Equity of the Operating Partnership Limited Partners' Equity of the Operating Partnership - Outstanding Cumulative Redeemable Preferred Stock(Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Preferred Units [Line Items]
Preferred Units, Outstanding	5,290,000		9,740,000
Preferred Unit Redemptions [Abstract]
Preferred Stock Redemption Discount	$ 3,729,000
Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Preferred Units, Outstanding	5,290,000		9,740,000
Preferred Unit Redemptions [Abstract]
Preferred Stock Redemption Discount	3,729,000	0
Series B Preferred Stock [Member]
Preferred Units [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.45%
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount	95,000,000
Series B Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.45%
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount	95,000,000
Series E Preferred Stock [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	20,000,000
Preferred Units, Outstanding	400,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.00%
preferred units redeemable date	Jun. 16, 2010
Redeemable preferred units Exchangeable date	6/16/15 into Series E Cumulative Redeemable Preferred Shares of the Trust
Series E Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	20,000,000
Preferred Units, Outstanding	400,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.00%
preferred units redeemable date	Jun. 16, 2010
Redeemable preferred units Exchangeable date	6/16/15 into Series E Cumulative Redeemable Preferred Shares of the Trust
Series F Preferred Stock [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	17,500,000
Preferred Units, Outstanding	350,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.65%
preferred units redeemable date	Jun. 30, 2010
Redeemable preferred units Exchangeable date	12/12/15 into Series F Cumulative Redeemable Preferred Shares of the Trust
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount	32,500,000
Payments for Repurchase of Preferred Stock and Preference Stock	26,000,000
Series F Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	17,500,000
Preferred Units, Outstanding	350,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.65%
preferred units redeemable date	Jun. 30, 2010
Redeemable preferred units Exchangeable date	12/12/15 into Series F Cumulative Redeemable Preferred Shares of the Trust
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount	32,500,000
Payments for Repurchase of Preferred Stock and Preference Stock	26,000,000
Series G Preferred Stock [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	27,000,000
Preferred Units, Outstanding	540,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.70%
preferred units redeemable date	Dec. 15, 2011
Redeemable preferred units Exchangeable date	12/15/16 into Series G Cumulative Redeemable Preferred Shares of the Trust
Series G Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	27,000,000
Preferred Units, Outstanding	540,000
Redeemable Preferred Units Liquidation Preference	50
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.70%
preferred units redeemable date	Dec. 15, 2011
Redeemable preferred units Exchangeable date	12/15/16 into Series G Cumulative Redeemable Preferred Shares of the Trust
Series H Preferred Stock [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	100,000,000
Preferred Units, Outstanding	4,000,000
Redeemable Preferred Units Liquidation Preference	25
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.40%
preferred units redeemable date	Aug. 21, 2012
Redeemable preferred units Exchangeable date	8/21/17 into Series H Cumulative Redeemable Preferred Shares of the Trust
Series H Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	100,000,000
Preferred Units, Outstanding	4,000,000
Redeemable Preferred Units Liquidation Preference	$ 25
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.40%
preferred units redeemable date	Aug. 21, 2012
Redeemable preferred units Exchangeable date	8/21/17 into Series H Cumulative Redeemable Preferred Shares of the Trust