Consolidated Statements of Comprehensive Income (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING REVENUE
Rental	$ 568,346,000	$ 458,081,000	$ 396,418,000
Operating expense reimbursement	224,285,000	187,849,000	163,861,000
Operating revenue	792,631,000	645,930,000	560,279,000
OPERATING EXPENSE
Rental property	138,124,000	114,617,000	104,431,000
Real estate taxes	101,814,000	79,918,000	65,697,000
General and administrative	63,327,000	74,564,000	64,686,000
Depreciation and amortization	231,943,000	173,784,000	135,523,000
Total operating expenses	535,208,000	442,883,000	370,337,000
Operating income	257,423,000	203,047,000	189,942,000
OTHER INCOME (EXPENSE)
Other Income	17,669,000	18,555,000	11,825,000
Interest expense	(151,887,000)	(127,115,000)	(103,363,000)
Total other income (expense)	(134,218,000)	(108,560,000)	(91,538,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	123,205,000	94,487,000	98,404,000
Gain on property dispositions	45,030,000	0	0
Income taxes	(2,967,000)	(2,799,000)	(976,000)
Equity in earnings (loss) of unconsolidated joint ventures	10,314,000	6,067,000	(681,000)
Income from continuing operations	175,582,000	97,755,000	96,747,000
Discontinued operations (including net gain on property dispositions of $46,631, $95,384 and $12,426 for the years ended December 31, 2014, 2013 and 2012, respectively)	48,581,000	121,839,000	51,004,000
Net income	224,163,000	219,594,000	147,751,000
Noncontrolling interest - operating partnership	(5,706,000)	(9,203,000)	(10,590,000)
Noncontrolling interest - consolidated joint ventures	(547,000)	(653,000)	275,000
Excess of preferred unit carrying amount over redemption			3,689,000
Excess of preferred unit carrying amount over redemption		(1,236,000)
Net income available to common shareholders	217,910,000	209,738,000	137,436,000
Comprehensive income attributable to common shareholders
Net income	224,163,000	219,594,000	147,751,000
Other comprehensive (loss) income - foreign currency translation	(14,415,000)	5,397,000	3,436,000
Other comprehensive income - change in net unrealized (loss) gain on derivative instruments	(1,961,000)	1,584,000	0
Other comprehensive (loss) income	(16,376,000)	6,981,000	3,436,000
Total comprehensive income	207,787,000	226,575,000	151,187,000
Less: comprehensive income attributable to noncontrolling interest	(5,870,000)	(9,995,000)	(10,422,000)
Comprehensive income attributable to common shareholders	201,917,000	216,580,000	140,765,000
Weighted average number of common shares outstanding
Basic	147,216	130,180	116,863
Diluted	147,886	130,909	117,694
Amounts attributable to common shareholders
Income from continuing operations	170,471,000	91,274,000	88,008,000
Discontinued operations	47,439,000	118,464,000	49,428,000
Net income available to common shareholders	217,910,000	209,738,000	137,436,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	568,346,000	458,081,000	396,418,000
Operating expense reimbursement	224,285,000	187,849,000	163,861,000
Operating revenue	792,631,000	645,930,000	560,279,000
OPERATING EXPENSE
Rental property	138,124,000	114,617,000	104,431,000
Real estate taxes	101,814,000	79,918,000	65,697,000
General and administrative	63,327,000	74,564,000	64,686,000
Depreciation and amortization	231,943,000	173,784,000	135,523,000
Total operating expenses	535,208,000	442,883,000	370,337,000
Operating income	257,423,000	203,047,000	189,942,000
OTHER INCOME (EXPENSE)
Other Income	17,669,000	18,555,000	11,825,000
Interest expense	(151,887,000)	(127,115,000)	(103,363,000)
Total other income (expense)	(134,218,000)	(108,560,000)	(91,538,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	123,205,000	94,487,000	98,404,000
Gain on property dispositions	45,030,000	0	0
Income taxes	(2,967,000)	(2,799,000)	(976,000)
Equity in earnings (loss) of unconsolidated joint ventures	10,314,000	6,067,000	(681,000)
Income from continuing operations	175,582,000	97,755,000	96,747,000
Discontinued operations (including net gain on property dispositions of $46,631, $95,384 and $12,426 for the years ended December 31, 2014, 2013 and 2012, respectively)	48,581,000	121,839,000	51,004,000
Net income	224,163,000	219,594,000	147,751,000
Noncontrolling interest - consolidated joint ventures	(547,000)	(653,000)	275,000
Preferred unit distributions	(472,000)	(2,119,000)	(9,902,000)
Excess of preferred unit carrying amount over redemption	0		3,689,000
Excess of preferred unit carrying amount over redemption	0	(1,236,000)
Net income available to common shareholders	223,144,000	215,586,000	141,813,000
Comprehensive income attributable to common shareholders
Net income	224,163,000	219,594,000	147,751,000
Other comprehensive (loss) income - foreign currency translation	(14,415,000)	5,397,000	3,436,000
Other comprehensive income - change in net unrealized (loss) gain on derivative instruments	(1,961,000)	1,584,000	0
Other comprehensive (loss) income	(16,376,000)	6,981,000	3,436,000
Total comprehensive income	207,787,000	226,575,000	151,187,000
Weighted average number of common shares outstanding
Basic	150,770	133,858	120,623
Diluted	151,440	134,587	121,454
Net Income Allocated to General Partners	217,910,000	209,738,000	137,436,000
Net Income Allocated to Limited Partners	5,706,000	9,203,000	10,590,000
Amounts attributable to common shareholders
Income from continuing operations	175,035,000	97,102,000	97,022,000
Net income available to common shareholders	$ 223,144,000	$ 215,586,000	$ 141,813,000
Common shares [Member]
Basic:
Income from continuing operations	$ 1.16	$ 0.70	$ 0.75
Income from discontinued operations	$ 0.32	$ 0.91	$ 0.43
Income per common share - basic	$ 1.48	$ 1.61	$ 1.18
Diluted:
Income from continuing operations	$ 1.15	$ 0.70	$ 0.75
Income from discontinued operations	$ 0.32	$ 0.90	$ 0.42
Income per common share - diluted	$ 1.47	$ 1.60	$ 1.17
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income from continuing operations	$ 1.16	$ 0.70	$ 0.75
Income from discontinued operations	$ 0.32	$ 0.91	$ 0.43
Income per common share - basic	$ 1.48	$ 1.61	$ 1.18
Diluted:
Income from continuing operations	$ 1.15	$ 0.70	$ 0.75
Income from discontinued operations	$ 0.32	$ 0.90	$ 0.42
Income per common share - diluted	$ 1.47	$ 1.60	$ 1.17