Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
OPERATING REVENUE
Rental	$ 145,009,000	$ 143,294,000	$ 440,962,000	$ 421,620,000
Operating expense reimbursement	53,963,000	55,062,000	168,430,000	167,326,000
Total operating revenue	198,972,000	198,356,000	609,392,000	588,946,000
OPERATING EXPENSE
Rental property	31,454,000	33,105,000	98,973,000	103,728,000
Real estate taxes	25,953,000	25,595,000	78,579,000	75,812,000
General and administrative	15,573,000	14,748,000	51,428,000	48,077,000
Depreciation and amortization	55,718,000	58,578,000	171,347,000	173,184,000
Impairment - real estate assets	0	0	16,775,000	0
Total operating expenses	128,698,000	132,026,000	417,102,000	400,801,000
Operating income	70,274,000	66,330,000	192,290,000	188,145,000
OTHER INCOME (EXPENSE)
Other income	4,959,000	6,233,000	17,911,000	11,786,000
Interest expense	(33,559,000)	(37,958,000)	(103,295,000)	(115,635,000)
Total other income (expense)	(28,600,000)	(31,725,000)	(85,384,000)	(103,849,000)
Income before gain (loss) on property dispositions, income taxes and equity in (loss) earnings of unconsolidated joint ventures	41,674,000	34,605,000	106,906,000	84,296,000
Gain (loss) on property dispositions	53,467,000	(20,000)	56,987,000	1,878,000
Income taxes	(599,000)	(859,000)	(2,613,000)	(2,083,000)
Equity in (loss) earnings of unconsolidated joint ventures	(847,000)	1,592,000	805,000	7,297,000
Income from continuing operations	93,695,000	35,318,000	162,085,000	91,388,000
Discontinued operations (including net gain on property dispositions of $38 for the three months ended September 30, 2014 and $46,292 for the nine months ended September 30, 2014)	0	133,000	0	48,276,000
Net income	93,695,000	35,451,000	162,085,000	139,664,000
Noncontrolling interest – operating partnership	(2,306,000)	(944,000)	(4,117,000)	(3,618,000)
Noncontrolling interest - consolidated joint ventures	(58,000)	(84,000)	(171,000)	(474,000)
Net income available to common shareholders	91,331,000	34,423,000	157,797,000	135,572,000
Comprehensive income attributable to common shareholders
Net income	93,695,000	35,451,000	162,085,000	139,664,000
Other comprehensive loss - foreign currency translation	(7,970,000)	(13,000,000)	(6,229,000)	(5,189,000)
Other comprehensive (loss) income - derivative instruments	(1,220,000)	666,000	(1,539,000)	(990,000)
Other comprehensive loss	(9,190,000)	(12,334,000)	(7,768,000)	(6,179,000)
Total comprehensive income	84,505,000	23,117,000	154,317,000	133,485,000
Less: comprehensive income attributable to noncontrolling interest	(2,148,000)	(739,000)	(4,105,000)	(3,948,000)
Comprehensive income attributable to common shareholders	$ 82,357,000	$ 22,378,000	$ 150,212,000	$ 129,537,000
Weighted average number of common shares outstanding
Basic	148,582	147,422	148,594	146,987
Diluted	149,176	148,088	149,220	147,661
Amounts attributable to common shareholders
Income from continuing operations	$ 91,331,000	$ 34,293,000	$ 157,797,000	$ 88,430,000
Discontinued operations	0	130,000	0	47,142,000
Net income available to common shareholders	91,331,000	34,423,000	157,797,000	135,572,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	145,009,000	143,294,000	440,962,000	421,620,000
Operating expense reimbursement	53,963,000	55,062,000	168,430,000	167,326,000
Total operating revenue	198,972,000	198,356,000	609,392,000	588,946,000
OPERATING EXPENSE
Rental property	31,454,000	33,105,000	98,973,000	103,728,000
Real estate taxes	25,953,000	25,595,000	78,579,000	75,812,000
General and administrative	15,573,000	14,748,000	51,428,000	48,077,000
Depreciation and amortization	55,718,000	58,578,000	171,347,000	173,184,000
Impairment - real estate assets			16,775,000	0
Total operating expenses	128,698,000	132,026,000	417,102,000	400,801,000
Operating income	70,274,000	66,330,000	192,290,000	188,145,000
OTHER INCOME (EXPENSE)
Other income	4,959,000	6,233,000	17,911,000	11,786,000
Interest expense	(33,559,000)	(37,958,000)	(103,295,000)	(115,635,000)
Total other income (expense)	(28,600,000)	(31,725,000)	(85,384,000)	(103,849,000)
Income before gain (loss) on property dispositions, income taxes and equity in (loss) earnings of unconsolidated joint ventures	41,674,000	34,605,000	106,906,000	84,296,000
Gain (loss) on property dispositions	53,467,000	(20,000)	56,987,000	1,878,000
Income taxes	(599,000)	(859,000)	(2,613,000)	(2,083,000)
Equity in (loss) earnings of unconsolidated joint ventures	(847,000)	1,592,000	805,000	7,297,000
Income from continuing operations	93,695,000	35,318,000	162,085,000	91,388,000
Discontinued operations (including net gain on property dispositions of $38 for the three months ended September 30, 2014 and $46,292 for the nine months ended September 30, 2014)	0	133,000	0	48,276,000
Net income	93,695,000	35,451,000	162,085,000	139,664,000
Noncontrolling interest - consolidated joint ventures	(58,000)	(84,000)	(171,000)	(474,000)
Preferred unit distributions	(118,000)	(118,000)	(354,000)	(354,000)
Net income available to common shareholders	93,519,000	35,249,000	161,560,000	138,836,000
Comprehensive income attributable to common shareholders
Net income	93,695,000	35,451,000	162,085,000	139,664,000
Other comprehensive loss - foreign currency translation	(7,970,000)	(13,000,000)	(6,229,000)	(5,189,000)
Other comprehensive (loss) income - derivative instruments	(1,220,000)	666,000	(1,539,000)	(990,000)
Other comprehensive loss	(9,190,000)	(12,334,000)	(7,768,000)	(6,179,000)
Total comprehensive income	$ 84,505,000	$ 23,117,000	$ 154,317,000	$ 133,485,000
Weighted average number of common shares outstanding
Basic	152,121	150,976	152,134	150,541
Diluted	152,715	151,642	152,760	151,215
Net income allocated to general partners	$ 91,331,000	$ 34,423,000	$ 157,797,000	$ 135,572,000
Net income allocated to limited partners	2,306,000	944,000	4,117,000	3,618,000
Amounts attributable to common shareholders
Income from continuing operations	93,637,000	35,234,000	161,914,000	90,914,000
Net income available to common shareholders	$ 93,519,000	$ 35,249,000	$ 161,560,000	$ 138,836,000
Common shares [Member]
Basic:
Income from continuing operations	$ 0.61	$ 0.23	$ 1.06	$ 0.60
Income from discontinued operations	0.00	0.00	0.00	0.32
Income per common share - basic	0.61	0.23	1.06	0.92
Diluted:
Income from continuing operations	0.61	0.23	1.06	0.60
Income from discontinued operations	0.00	0.00	0.00	0.32
Income per common share - diluted	0.61	0.23	1.06	0.92
Distributions per common share or unit	0.475	0.475	1.425	1.425
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income from continuing operations	0.61	0.23	1.06	0.60
Income from discontinued operations	0.00	0.00	0.00	0.32
Income per common share - basic	0.61	0.23	1.06	0.92
Diluted:
Income from continuing operations	0.61	0.23	1.06	0.60
Income from discontinued operations	0.00	0.00	0.00	0.32
Income per common share - diluted	0.61	0.23	1.06	0.92
Distributions per common share or unit	$ 0.475	$ 0.475	$ 1.425	$ 1.425