Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
OPERATING REVENUE
Rental	$ 128,044	$ 116,666	$ 375,702	$ 348,955
Operating expense reimbursement	55,342	51,017	160,476	148,187
Total operating revenue	183,386	167,683	536,178	497,142
OPERATING EXPENSE
Rental property	35,213	33,934	99,746	93,840
Real estate taxes	22,107	19,517	65,007	59,167
General and administrative	17,231	14,610	53,552	46,391
Depreciation and amortization	46,036	40,149	135,560	120,337
Total operating expenses	120,587	108,210	353,865	319,735
Operating income	62,799	59,473	182,313	177,407
OTHER INCOME (EXPENSE)
Interest and other income	2,620	2,340	7,612	7,055
Interest expense	(37,412)	(30,772)	(101,141)	(88,941)
Total other income (expense)	(34,792)	(28,432)	(93,529)	(81,886)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	28,007	31,041	88,784	95,521
Gain on property dispositions	1,958	2,001	6,829	2,859
Income taxes	(629)	(321)	(1,780)	(645)
Equity in earnings (loss) of unconsolidated joint ventures	650	(3,082)	3,973	(1,397)
Income from continuing operations	29,986	29,639	97,806	96,338
Discontinued operations (including net gain on property dispositions of $29 for the quarter ended September 30, 2013 and net loss of $1,540 for the quarter ended September 30, 2012)	(38)	259	50,041	10,842
Net income	29,948	29,898	147,847	107,180
Noncontrolling interest – operating partnership	(843)	(2,092)	(7,394)	(8,174)
Noncontrolling interest - consolidated joint ventures	(406)	0	(406)	0
Preferred stock redemption premium			(1,236)
Net income available to common shareholders	28,699	27,806	140,047	99,006
Comprehensive income attributable to common shareholders
Net income	29,948	29,898	147,847	107,180
Other comprehensive income	4,927	2,245	115	3,047
Total comprehensive income	34,875	32,143	147,962	110,227
Less: comprehensive income attributable to noncontrolling interest	(1,370)	(2,161)	(7,777)	(8,269)
Comprehensive income attributable to common shareholders	33,505	29,982	140,185	101,958
Basic:
Income from continuing operations	$ 0.21	$ 0.24	$ 0.73	$ 0.76
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.39	$ 0.09
Income per common share - basic	$ 0.21	$ 0.24	$ 1.12	$ 0.85
Diluted:
Income from continuing operations	$ 0.21	$ 0.24	$ 0.72	$ 0.75
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.39	$ 0.09
Income per common share - diluted	$ 0.21	$ 0.24	$ 1.11	$ 0.84
Distributions per common share or unit	$ 0.475	$ 0.475	$ 1.425	$ 1.425
Weighted average number of common shares outstanding
Basic	135,628	117,141	124,889	116,625
Diluted	136,328	118,043	125,655	117,462
Amounts attributable to common shareholders
Income from continuing operations	28,736	27,555	91,442	88,500
Discontinued operations	(37)	251	48,605	10,506
Net income available to common shareholders	28,699	27,806	140,047	99,006
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	128,044	116,666	375,702	348,955
Operating expense reimbursement	55,342	51,017	160,476	148,187
Total operating revenue	183,386	167,683	536,178	497,142
OPERATING EXPENSE
Rental property	35,213	33,934	99,746	93,840
Real estate taxes	22,107	19,517	65,007	59,167
General and administrative	17,231	14,610	53,552	46,391
Depreciation and amortization	46,036	40,149	135,560	120,337
Total operating expenses	120,587	108,210	353,865	319,735
Operating income	62,799	59,473	182,313	177,407
OTHER INCOME (EXPENSE)
Interest and other income	2,620	2,340	7,612	7,055
Interest expense	(37,412)	(30,772)	(101,141)	(88,941)
Total other income (expense)	(34,792)	(28,432)	(93,529)	(81,886)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	28,007	31,041	88,784	95,521
Gain on property dispositions	1,958	2,001	6,829	2,859
Income taxes	(629)	(321)	(1,780)	(645)
Equity in earnings (loss) of unconsolidated joint ventures	650	(3,082)	3,973	(1,397)
Income from continuing operations	29,986	29,639	97,806	96,338
Discontinued operations (including net gain on property dispositions of $29 for the quarter ended September 30, 2013 and net loss of $1,540 for the quarter ended September 30, 2012)	(38)	259	50,041	10,842
Net income	29,948	29,898	147,847	107,180
Noncontrolling interest - consolidated joint ventures	(406)	0	(406)	0
Preferred unit distributions	(118)	(1,211)	(2,001)	(8,690)
Preferred stock redemption premium			(1,236)
Preferred stock redemption discount				3,689
Net income available to common shareholders	29,424	28,687	144,204	102,179
Comprehensive income attributable to common shareholders
Net income	29,948	29,898	147,847	107,180
Other comprehensive income	4,927	2,245	115	3,047
Total comprehensive income	34,875	32,143	147,962	110,227
Basic:
Income from continuing operations	$ 0.21	$ 0.24	$ 0.73	$ 0.76
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.39	$ 0.09
Income per common share - basic	$ 0.21	$ 0.24	$ 1.12	$ 0.85
Diluted:
Income from continuing operations	$ 0.21	$ 0.24	$ 0.72	$ 0.75
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.39	$ 0.09
Income per common share - diluted	$ 0.21	$ 0.24	$ 1.11	$ 0.84
Distributions per common share or unit	$ 0.475	$ 0.475	$ 1.425	$ 1.425
Weighted average number of common shares outstanding
Basic	139,320	120,880	128,595	120,396
Diluted	140,020	121,782	129,361	121,233
Net income allocated to general partners	28,699	27,806	140,047	99,006
Net income allocated to limited partners	843	2,092	7,394	8,174
Amounts attributable to common shareholders
Income from continuing operations	29,580	29,639	97,400	96,338
Net income available to common shareholders	$ 29,424	$ 28,687	$ 144,204	$ 102,179