Consolidated Statements of Comprehensive Income (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
OPERATING REVENUE
Rental	$ 148,585,000	$ 138,949,000
Operating expense reimbursement	58,316,000	58,681,000
Total operating revenue	206,901,000	197,630,000
OPERATING EXPENSE
Rental property	35,571,000	38,641,000
Real estate taxes	26,164,000	24,501,000
General and administrative	18,802,000	18,356,000
Depreciation and amortization	58,796,000	56,734,000
Impairment - real estate assets	15,739,000	0
Total operating expenses	155,072,000	138,232,000
Operating income	51,829,000	59,398,000
OTHER INCOME (EXPENSE)
Other income	6,371,000	2,439,000
Interest expense	(34,670,000)	(39,207,000)
Total other income (expense)	(28,299,000)	(36,768,000)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	23,530,000	22,630,000
Gain on property dispositions	2,271,000	0
Income taxes	(845,000)	(531,000)
Equity in earnings of unconsolidated joint ventures	6,906,000	4,159,000
Income from continuing operations	31,862,000	26,258,000
Discontinued operations (including net gain on property dispositions of $46,115 for the three months ended March 31, 2014)	0	47,848,000
Net income	31,862,000	74,106,000
Noncontrolling interest – operating partnership	(853,000)	(1,853,000)
Noncontrolling interest - consolidated joint ventures	(58,000)	(353,000)
Net income available to common shareholders	30,951,000	71,900,000
Comprehensive income attributable to common shareholders
Net income	31,862,000	74,106,000
Other comprehensive (loss) income - foreign currency translation	(10,410,000)	1,346,000
Other comprehensive loss - derivative instruments	(947,000)	(511,000)
Other comprehensive (loss) income	(11,357,000)	835,000
Total comprehensive income	20,505,000	74,941,000
Less: comprehensive income attributable to noncontrolling interest	(648,000)	(2,226,000)
Comprehensive income attributable to common shareholders	19,857,000	72,715,000
Weighted average number of common shares outstanding
Basic	148,315	146,425
Diluted	149,031	147,095
Amounts attributable to common shareholders
Income from continuing operations	30,951,000	25,179,000
Discontinued operations	0	46,721,000
Net income available to common shareholders	30,951,000	71,900,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	148,585,000	138,949,000
Operating expense reimbursement	58,316,000	58,681,000
Total operating revenue	206,901,000	197,630,000
OPERATING EXPENSE
Rental property	35,571,000	38,641,000
Real estate taxes	26,164,000	24,501,000
General and administrative	18,802,000	18,356,000
Depreciation and amortization	58,796,000	56,734,000
Impairment - real estate assets	15,739,000	0
Total operating expenses	155,072,000	138,232,000
Operating income	51,829,000	59,398,000
OTHER INCOME (EXPENSE)
Other income	6,371,000	2,439,000
Interest expense	(34,670,000)	(39,207,000)
Total other income (expense)	(28,299,000)	(36,768,000)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	23,530,000	22,630,000
Gain on property dispositions	2,271,000	0
Income taxes	(845,000)	(531,000)
Equity in earnings of unconsolidated joint ventures	6,906,000	4,159,000
Income from continuing operations	31,862,000	26,258,000
Discontinued operations (including net gain on property dispositions of $46,115 for the three months ended March 31, 2014)	0	47,848,000
Net income	31,862,000	74,106,000
Noncontrolling interest - consolidated joint ventures	(58,000)	(353,000)
Preferred unit distributions	(118,000)	(118,000)
Net income available to common shareholders	31,686,000	73,635,000
Comprehensive income attributable to common shareholders
Net income	31,862,000	74,106,000
Other comprehensive (loss) income - foreign currency translation	(10,410,000)	1,346,000
Other comprehensive loss - derivative instruments	(947,000)	(511,000)
Other comprehensive (loss) income	(11,357,000)	835,000
Total comprehensive income	20,505,000	74,941,000
Weighted average number of common shares outstanding
Basic	151,856	149,981
Diluted	152,572	150,651
Net income allocated to general partners	30,951,000	71,900,000
Net income allocated to limited partners	853,000	1,853,000
Amounts attributable to common shareholders
Income from continuing operations	31,804,000	25,905,000
Net income available to common shareholders	$ 31,686,000	$ 73,635,000
Common shares [Member]
Basic:
Income from continuing operations	$ 0.21	$ 0.17
Income from discontinued operations	$ 0.00	$ 0.32
Income per common share - basic	$ 0.21	$ 0.49
Diluted:
Income from continuing operations	$ 0.21	$ 0.17
Income from discontinued operations	$ 0.00	$ 0.32
Income per common share - diluted	$ 0.21	$ 0.49
Distributions per common share or unit	$ 0.475	$ 0.475
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income from continuing operations	$ 0.21	$ 0.17
Income from discontinued operations	$ 0.00	$ 0.32
Income per common share - basic	$ 0.21	$ 0.49
Diluted:
Income from continuing operations	$ 0.21	$ 0.17
Income from discontinued operations	$ 0.00	$ 0.32
Income per common share - diluted	$ 0.21	$ 0.49
Distributions per common share or unit	$ 0.475	$ 0.475