Limited Partners' Equity of the Operating Partnership Limited Partners' Equity of the Operating Partnership - Outstanding Cumulative Redeemable Preferred Stock(Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Preferred Units [Line Items]
Preferred Units, Outstanding	1,290,000		1,290,000		9,740,000
Preferred Stock Redemption Premium	$ 40,000
Preferred Unit Redemptions [Abstract]
Preferred Stock Redemption Discount			3,689,000
Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Preferred Units, Outstanding	1,290,000		1,290,000		9,740,000
Preferred Stock Redemption Premium	40,000
Preferred Unit Redemptions [Abstract]
Preferred Stock Redemption Discount		0	3,689,000	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		20,000,000
Preferred Units, Outstanding	400,000		400,000
Redeemable Preferred Units Liquidation Preference	50		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		20,000,000
Preferred Units, Outstanding	400,000		400,000
Redeemable Preferred Units Liquidation Preference	50		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		17,500,000
Preferred Units, Outstanding	350,000		350,000
Redeemable Preferred Units Liquidation Preference	50		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			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		17,500,000
Preferred Units, Outstanding	350,000		350,000
Redeemable Preferred Units Liquidation Preference	50		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			26,000,000
Series G Preferred Stock [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	27,000,000		27,000,000
Preferred Units, Outstanding	540,000		540,000
Redeemable Preferred Units Liquidation Preference	50		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		27,000,000
Preferred Units, Outstanding	540,000		540,000
Redeemable Preferred Units Liquidation Preference	50		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]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount			7.40%
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount			100,000,000
Series H Preferred Stock [Member] | Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount			7.40%
Preferred Unit Redemptions [Abstract]
Preferred Stock, Redemption Amount			$ 100,000,000