Consolidated Statements of Comprehensive Income (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING REVENUE
Rental	$ 458,081,000	$ 396,418,000	$ 379,811,000
Operating expense reimbursement	187,849,000	163,861,000	153,888,000
Operating revenue	645,930,000	560,279,000	533,699,000
OPERATING EXPENSE
Rental property	114,617,000	104,431,000	95,192,000
Real estate taxes	79,918,000	65,697,000	62,108,000
General and administrative	74,564,000	64,686,000	59,186,000
Depreciation and amortization	173,784,000	135,523,000	126,218,000
Total operating expenses	442,883,000	370,337,000	342,704,000
Operating income	203,047,000	189,942,000	190,995,000
OTHER INCOME (EXPENSE)
Interest and other income	9,879,000	8,745,000	8,137,000
Interest expense	(127,115,000)	(103,363,000)	(101,988,000)
Total other income (expense)	(117,236,000)	(94,618,000)	(93,851,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	85,811,000	95,324,000	97,144,000
Gain on property dispositions	8,676,000	3,080,000	5,025,000
Income taxes	(2,799,000)	(976,000)	(1,020,000)
Equity in earnings (loss) of unconsolidated joint ventures	6,067,000	(681,000)	3,496,000
Income from continuing operations	97,755,000	96,747,000	104,645,000
Discontinued operations (including net gain on property dispositions of $95,384, $12,426 and $60,582 for the years ended December 31, 2013, 2012 and 2011, respectively)	121,839,000	51,004,000	106,065,000
Net income	219,594,000	147,751,000	210,710,000
Noncontrolling interest - operating partnership	(9,203,000)	(10,590,000)	(27,222,000)
Noncontrolling interest - consolidated joint ventures	(653,000)	275,000	511,000
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	209,738,000	137,436,000	183,999,000
Comprehensive income attributable to common shareholders
Net income	219,594,000	147,751,000	210,710,000
Other comprehensive income (loss) - foreign currency translation	5,397,000	3,436,000	(280,000)
Other comprehensive income - change in net unrealized gain on derivatives	1,584,000	0	0
Other Comprehensive Income (Loss), Net of Tax	6,981,000	3,436,000	(280,000)
Comprehensive income	226,575,000	151,187,000	210,430,000
Less: comprehensive income attributable to noncontrolling interest	(9,995,000)	(10,422,000)	(26,706,000)
Comprehensive income attributable to common shareholders	216,580,000	140,765,000	183,724,000
Basic:
Income from continuing operations	$ 0.70	$ 0.75	$ 0.71
Income from discontinued operations	$ 0.91	$ 0.43	$ 0.89
Income per common share - basic	$ 1.61	$ 1.18	$ 1.60
Diluted:
Income from continuing operations	$ 0.70	$ 0.75	$ 0.70
Income from discontinued operations	$ 0.90	$ 0.42	$ 0.89
Income per common share - diluted	$ 1.60	$ 1.17	$ 1.59
Weighted average number of common shares outstanding
Basic	130,180	116,863	114,755
Diluted	130,909	117,694	115,503
Amounts attributable to common shareholders
Income from continuing operations	91,274,000	88,008,000	81,392,000
Discontinued operations	118,464,000	49,428,000	102,607,000
Net income available to common shareholders	209,738,000	137,436,000	183,999,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	458,081,000	396,418,000	379,811,000
Operating expense reimbursement	187,849,000	163,861,000	153,888,000
Operating revenue	645,930,000	560,279,000	533,699,000
OPERATING EXPENSE
Rental property	114,617,000	104,431,000	95,192,000
Real estate taxes	79,918,000	65,697,000	62,108,000
General and administrative	74,564,000	64,686,000	59,186,000
Depreciation and amortization	173,784,000	135,523,000	126,218,000
Total operating expenses	442,883,000	370,337,000	342,704,000
Operating income	203,047,000	189,942,000	190,995,000
OTHER INCOME (EXPENSE)
Interest and other income	9,879,000	8,745,000	8,137,000
Interest expense	(127,115,000)	(103,363,000)	(101,988,000)
Total other income (expense)	(117,236,000)	(94,618,000)	(93,851,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	85,811,000	95,324,000	97,144,000
Gain on property dispositions	8,676,000	3,080,000	5,025,000
Income taxes	(2,799,000)	(976,000)	(1,020,000)
Equity in earnings (loss) of unconsolidated joint ventures	6,067,000	(681,000)	3,496,000
Income from continuing operations	97,755,000	96,747,000	104,645,000
Discontinued operations (including net gain on property dispositions of $95,384, $12,426 and $60,582 for the years ended December 31, 2013, 2012 and 2011, respectively)	121,839,000	51,004,000	106,065,000
Net income	219,594,000	147,751,000	210,710,000
Noncontrolling interest - consolidated joint ventures	(653,000)	275,000	511,000
Preferred unit distributions	(2,119,000)	(9,902,000)	(21,069,000)
Excess of preferred unit carrying amount over redemption		3,689,000	0
Excess of preferred unit carrying amount over redemption	(1,236,000)
Net income available to common shareholders	215,586,000	141,813,000	190,152,000
Comprehensive income attributable to common shareholders
Net income	219,594,000	147,751,000	210,710,000
Other comprehensive income (loss) - foreign currency translation	5,397,000	3,436,000	(280,000)
Other comprehensive income - change in net unrealized gain on derivatives	1,584,000	0	0
Other Comprehensive Income (Loss), Net of Tax	6,981,000	3,436,000	(280,000)
Comprehensive income	226,575,000	151,187,000	210,430,000
Basic:
Income from continuing operations	$ 0.70	$ 0.75	$ 0.71
Income from discontinued operations	$ 0.91	$ 0.43	$ 0.89
Income per common share - basic	$ 1.61	$ 1.18	$ 1.60
Diluted:
Income from continuing operations	$ 0.70	$ 0.75	$ 0.70
Income from discontinued operations	$ 0.90	$ 0.42	$ 0.89
Income per common share - diluted	$ 1.60	$ 1.17	$ 1.59
Weighted average number of common shares outstanding
Basic	133,858	120,623	118,624
Diluted	134,587	121,454	119,372
Net Income Allocated to General Partners	209,738,000	137,436,000	183,999,000
Net Income Allocated to Limited Partners	9,203,000	10,590,000	27,222,000
Amounts attributable to common shareholders
Income from continuing operations	97,102,000	97,022,000	105,156,000
Net income available to common shareholders	$ 215,586,000	$ 141,813,000	$ 190,152,000