Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Preferred Units [Line Items]
Preferred Units, Outstanding	1,290,000	9,740,000
Preferred Units, Total Annual Cash Distributions	$ 9,900,000	$ 21,000,000	$ 21,000,000
Series I-2 [Member]
Preferred Units [Line Items]
Preferred Units, Outstanding	301,483	301,483
Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Preferred Units, Outstanding	1,290,000	9,740,000
Preferred Units, Total Annual Cash Distributions	9,900,000	21,000,000	21,000,000
Liberty Property Limited Partnership [Member] | Series I-2 [Member]
Preferred Units [Line Items]
Preferred Units, Outstanding	301,483	301,483
Unredeemed [Member] | Series I-2 [Member]
Preferred Units [Line Items]
Noncontrolling Interest in Operating Partnerships	7,537,000
Preferred Units, Outstanding	301,000
Redeemable Preferred Units Liquidation Preference	$ 25
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.25%
Preferred Units, Total Annual Cash Distributions	471,000	57,000
Redeemed [Member] | Series I-1 [Member]
Preferred Units [Line Items]
Preferred Units, Issued		362,369
Preferred Stock, Value, Issued		$ 9,100,000
Preferred units, Redeemed		362,369