Other Comprehensive Income of the Operating Partnership (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Comprehensive Income [Line Items]
Other comprehensive income (loss) - foreign currency translation	$ 3,436	$ (280)	$ (2,582)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	140,765	183,724	125,268
Liberty Property Limited Partnership [Member]
Other Comprehensive Income [Line Items]
Other comprehensive income (loss) - foreign currency translation	$ 3,436	$ (280)	$ (2,582)

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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Before tax and net of reclassification adjustments of the change in the balance sheet adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency of the reporting entity. Also includes the following: gain (loss) on foreign currency forward exchange contracts; foreign currency transactions designated as hedges of net investment in a foreign entity and intercompany foreign currency transactions that are of a long-term nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements; and gain (loss) on a derivative instrument or nonderivative financial instrument that may give rise to a foreign currency transaction gain (loss) that has been designated and qualified as a hedging instrument for hedging of the foreign currency exposure of a net investment in a foreign operation.

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