Owners' Equity - Operating Partnership(Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Limited Partners' Capital Account [Line Items]
Limited Partners' Capital Account, Units Outstanding	3,713,851	3,808,746
Preferred Units, Total Annual Cash Distributions	$ 9,900,000	$ 21,000,000	$ 21,000,000
Preferred Units, Outstanding	1,290,000	9,740,000
Preferred Stock Redemption Discount	3,689,000
Series B Preferred Stock [Member]
Limited Partners' Capital Account [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.45%
Preferred Units, Annual Cash Distributions	$ 0.45	$ 1.86	$ 1.86
Stock Redeemed or Called During Period, Value	95,000,000
Series E Preferred Stock [Member]
Limited Partners' Capital Account [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
Preferred Units, Annual Cash Distributions	$ 3.50	$ 3.50	$ 3.50
Series F Preferred Stock [Member]
Limited Partners' Capital Account [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 Units, Annual Cash Distributions	$ 1.43	$ 3.33	$ 3.33
Stock Redeemed or Called During Period, Value	32,500,000
Payments for Repurchase of Preferred Stock and Preference Stock	26,000,000
Series G Preferred Stock [Member]
Limited Partners' Capital Account [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
Preferred Units, Annual Cash Distributions	$ 3.35	$ 3.35	$ 3.35
Series H Preferred Stock [Member]
Limited Partners' Capital Account [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.40%
Preferred Units, Annual Cash Distributions	$ 0.77	$ 1.85	$ 1.85
Stock Redeemed or Called During Period, Value	100,000,000
Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Preferred Units, Total Annual Cash Distributions	9,900,000	21,000,000	21,000,000
market value of the outstanding common units	132,900,000
Preferred Units, Outstanding	1,290,000	9,740,000
Preferred Stock Redemption Discount	3,689,000	0	0
Liberty Property Limited Partnership [Member] | Series B Preferred Stock [Member]
Limited Partners' Capital Account [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.45%
Preferred Units, Annual Cash Distributions	$ 0.45	$ 1.86	$ 1.86
Stock Redeemed or Called During Period, Value	95,000,000
Liberty Property Limited Partnership [Member] | Series E Preferred Stock [Member]
Limited Partners' Capital Account [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
Preferred Units, Annual Cash Distributions	$ 3.50	$ 3.50	$ 3.50
Liberty Property Limited Partnership [Member] | Series F Preferred Stock [Member]
Limited Partners' Capital Account [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 Units, Annual Cash Distributions	$ 1.43	$ 3.33	$ 3.33
Stock Redeemed or Called During Period, Value	32,500,000
Payments for Repurchase of Preferred Stock and Preference Stock	26,000,000
Liberty Property Limited Partnership [Member] | Series G Preferred Stock [Member]
Limited Partners' Capital Account [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
Preferred Units, Annual Cash Distributions	$ 3.35	$ 3.35	$ 3.35
Liberty Property Limited Partnership [Member] | Series H Preferred Stock [Member]
Limited Partners' Capital Account [Line Items]
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	7.40%
Preferred Units, Annual Cash Distributions	$ 0.77	$ 1.85	$ 1.85
Stock Redeemed or Called During Period, Value	100,000,000
Conversion Ratio of Preferred Units to Preferred Shares [Member] [Member]
Limited Partners' Capital Account [Line Items]
Preferred Unit, Convertible to Preferred Shares	1
Preferred Shares, Converted from Common Unit	1
Conversion Ratio of Preferred Units to Preferred Shares [Member] [Member] | Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Preferred Unit, Convertible to Preferred Shares	1
Preferred Shares, Converted from Common Unit	1
Continuous Equity Offering [Member]
Limited Partners' Capital Account [Line Items]
Common stock, Continuous equity offering program, Max amount of equity	200,000,000
Continuous Equity Offering [Member] | Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Common stock, Continuous equity offering program, Max amount of equity	$ 200,000,000
Common Stock [Member] | Continuous Equity Offering [Member]
Limited Partners' Capital Account [Line Items]
Stock Issued During Period, Shares, Other	0	0	0
Common Stock [Member] | Continuous Equity Offering [Member] | Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Stock Issued During Period, Shares, Other	0	0	0