Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
OPERATING REVENUE
Rental	$ 129,356,000	$ 140,697,000	$ 377,706,000	$ 418,896,000
Operating expense reimbursement	40,121,000	50,160,000	120,523,000	148,757,000
Development service fee income	24,176,000	0	53,920,000	0
Total operating revenue	193,653,000	190,857,000	552,149,000	567,653,000
OPERATING EXPENSE
Rental property	18,941,000	26,496,000	56,541,000	79,752,000
Real estate taxes	23,258,000	25,968,000	69,783,000	76,490,000
General and administrative	11,910,000	15,379,000	43,949,000	51,888,000
Expensed pursuit costs	4,772,000	772,000	4,957,000	882,000
Depreciation and amortization	46,582,000	46,920,000	137,831,000	154,543,000
Development service fee expense	23,665,000	0	52,497,000	0
Impairment charges - real estate assets	9,650,000	0	9,650,000	0
Total operating expenses	138,778,000	115,535,000	375,208,000	363,555,000
Operating income	54,875,000	75,322,000	176,941,000	204,098,000
OTHER INCOME (EXPENSE)
Interest and other income	1,781,000	3,153,000	5,585,000	12,743,000
Loss on debt extinguishment	0	(3,494,000)	0	(3,494,000)
Interest expense	(23,060,000)	(29,528,000)	(67,345,000)	(91,071,000)
Total other income (expense)	(21,279,000)	(29,869,000)	(61,760,000)	(81,822,000)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	33,596,000	45,453,000	115,181,000	122,276,000
Gain on property dispositions	23,840,000	1,318,000	30,542,000	25,671,000
Income taxes	(582,000)	(80,000)	(1,528,000)	(1,633,000)
Equity in earnings of unconsolidated joint ventures	4,305,000	9,043,000	14,026,000	19,540,000
Income from continuing operations	61,159,000	55,734,000	158,221,000	165,854,000
Net income	61,159,000	55,734,000	158,221,000	165,854,000
Noncontrolling interest – operating partnership	(1,545,000)	(1,424,000)	(4,044,000)	(4,250,000)
Noncontrolling interest - consolidated joint ventures	(75,000)	(57,000)	(195,000)	(170,000)
Net income available to common shareholders	59,539,000	54,253,000	153,982,000	161,434,000
Comprehensive income attributable to common shareholders
Net income	61,159,000	55,734,000	158,221,000	165,854,000
Other comprehensive income (loss) - foreign currency translation	5,634,000	(4,407,000)	16,314,000	(23,003,000)
Other comprehensive income (loss) - derivative instruments	91,000	663,000	366,000	(1,132,000)
Other comprehensive income (loss)	5,725,000	(3,744,000)	16,680,000	(24,135,000)
Total comprehensive income	66,884,000	51,990,000	174,901,000	141,719,000
Less: comprehensive income attributable to noncontrolling interest	(1,754,000)	(1,393,000)	(4,629,000)	(3,851,000)
Comprehensive income attributable to common shareholders	$ 65,130,000	$ 50,597,000	$ 170,272,000	$ 137,868,000
Weighted average number of common shares outstanding
Basic	146,811	146,215	146,678	146,121
Diluted	147,596	147,107	147,430	146,788
Amounts attributable to common shareholders
Net income available to common shareholders	$ 59,539,000	$ 54,253,000	$ 153,982,000	$ 161,434,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	129,356,000	140,697,000	377,706,000	418,896,000
Operating expense reimbursement	40,121,000	50,160,000	120,523,000	148,757,000
Development service fee income	24,176,000	0	53,920,000	0
Total operating revenue	193,653,000	190,857,000	552,149,000	567,653,000
OPERATING EXPENSE
Rental property	18,941,000	26,496,000	56,541,000	79,752,000
Real estate taxes	23,258,000	25,968,000	69,783,000	76,490,000
General and administrative	11,910,000	15,379,000	43,949,000	51,888,000
Expensed pursuit costs	4,772,000	772,000	4,957,000	882,000
Depreciation and amortization	46,582,000	46,920,000	137,831,000	154,543,000
Development service fee expense	23,665,000	0	52,497,000	0
Impairment charges - real estate assets	9,650,000	0	9,650,000	0
Total operating expenses	138,778,000	115,535,000	375,208,000	363,555,000
Operating income	54,875,000	75,322,000	176,941,000	204,098,000
OTHER INCOME (EXPENSE)
Interest and other income	1,781,000	3,153,000	5,585,000	12,743,000
Loss on debt extinguishment	0	(3,494,000)	0	(3,494,000)
Interest expense	(23,060,000)	(29,528,000)	(67,345,000)	(91,071,000)
Total other income (expense)	(21,279,000)	(29,869,000)	(61,760,000)	(81,822,000)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	33,596,000	45,453,000	115,181,000	122,276,000
Gain on property dispositions	23,840,000	1,318,000	30,542,000	25,671,000
Income taxes	(582,000)	(80,000)	(1,528,000)	(1,633,000)
Equity in earnings of unconsolidated joint ventures	4,305,000	9,043,000	14,026,000	19,540,000
Net income	61,159,000	55,734,000	158,221,000	165,854,000
Noncontrolling interest - consolidated joint ventures	(75,000)	(57,000)	(195,000)	(170,000)
Preferred unit distributions	(118,000)	(118,000)	(354,000)	(354,000)
Net income available to common shareholders	60,966,000	55,559,000	157,672,000	165,330,000
Comprehensive income attributable to common shareholders
Net income	61,159,000	55,734,000	158,221,000	165,854,000
Other comprehensive income (loss) - foreign currency translation	5,634,000	(4,407,000)	16,314,000	(23,003,000)
Other comprehensive income (loss) - derivative instruments	91,000	663,000	366,000	(1,132,000)
Other comprehensive income (loss)	5,725,000	(3,744,000)	16,680,000	(24,135,000)
Total comprehensive income	$ 66,884,000	$ 51,990,000	$ 174,901,000	$ 141,719,000
Weighted average number of common shares outstanding
Basic	150,339	149,751	150,206	149,659
Diluted	151,124	150,643	150,958	150,326
Net income allocated to general partners	$ 59,539,000	$ 54,253,000	$ 153,982,000	$ 161,434,000
Net income allocated to limited partners	1,545,000	1,424,000	4,044,000	4,250,000
Amounts attributable to common shareholders
Income from continuing operations	61,084,000	55,677,000	158,026,000	165,684,000
Net income available to common shareholders	$ 60,966,000	$ 55,559,000	$ 157,672,000	$ 165,330,000
Common shares [Member]
Basic:
Income per common share - basic	$ 0.41	$ 0.37	$ 1.05	$ 1.10
Diluted:
Income per common share - diluted	0.40	0.37	1.04	1.10
Distributions per common share or unit	0.40	0.475	1.20	1.425
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income per common share - basic	0.41	0.37	1.05	1.10
Diluted:
Income per common share - diluted	0.40	0.37	1.04	1.10
Distributions per common share or unit	$ 0.40	$ 0.475	$ 1.20	$ 1.425