Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING REVENUE
Rental		$ 486,195	$ 519,368	$ 561,434
Operating expense reimbursement		150,910	178,389	212,526
Development service fee income	[1]	82,673	12,941	0
Total operating revenue		719,778	710,698	773,960
OPERATING EXPENSE
Rental property		66,018	94,177	123,997
Real estate taxes		90,187	95,202	101,647
General and administrative		56,975	67,088	68,264
Expensed pursuit costs		5,066	1,016	605
Depreciation and amortization		175,137	196,705	217,864
Development service fee expense		85,805	12,165	0
Impairment - real estate assets		3,946	3,879	17,215
Total operating expense		483,134	470,232	529,592
Operating income		236,644	240,466	244,368
OTHER INCOME (EXPENSE)
Interest and other income		7,778	13,817	23,758
Loss on debt extinguishment		(49)	(27,099)	0
Interest expense		(88,857)	(112,299)	(133,557)
Total other income (expense)		(81,128)	(125,581)	(109,799)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures		155,516	114,885	134,569
Gain on property dispositions		100,387	219,270	100,314
Income taxes		(1,992)	(1,971)	(2,673)
Equity in earnings of unconsolidated joint ventures		17,155	21,970	3,149
Income from continuing operations		271,066	354,154	235,359
Discontinued operations (including net gain on property dispositions of $14,578 for the year ended December 31, 2017)		18,979	11,991	10,565
Net income		290,045	366,145	245,924
Noncontrolling interest – operating partnership		(7,224)	(9,070)	(6,192)
Noncontrolling interest – consolidated joint ventures		(481)	(258)	(249)
Income available to common shareholders		282,340	356,817	239,483
Comprehensive income attributable to common shareholders
Net income		290,045	366,145	245,924
Other comprehensive income (loss) - foreign currency translation		18,066	(34,744)	(12,540)
Other comprehensive income (loss) - derivative instruments		605	410	(488)
Other comprehensive loss		18,671	(34,334)	(13,028)
Total comprehensive income		308,716	331,811	232,896
Less: comprehensive income attributable to noncontrolling interest		(8,142)	(8,519)	(6,135)
Comprehensive income attributable to common shareholders		$ 300,574	$ 323,292	$ 226,761
Weighted average number of common shares outstanding
Basic (shares)		146,742	146,204	148,243
Diluted (shares)		147,541	146,889	148,843
Amounts attributable to common shareholders
Income from continuing operations		$ 263,805	$ 345,108	$ 229,164
Discontinued operations		18,535	11,709	10,319
Income available to common shareholders		$ 282,340	$ 356,817	$ 239,483
Common shares [Member]
Basic:
Income from continuing operations (USD per share/unit)		$ 1.79	$ 2.36	$ 1.55
Income from discontinued operations (USD per share/unit)		0.13	0.08	0.07
Income per common share - basic (USD per share/unit)		1.92	2.44	1.62
Diluted:
Income from continuing operations (USD per share/unit)		1.78	2.35	1.54
Income from discontinued operations (USD per share/unit)		0.13	0.08	0.07
Income per common share - diluted (USD per share/unit)		$ 1.91	$ 2.43	$ 1.61
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental		$ 486,195	$ 519,368	$ 561,434
Operating expense reimbursement		150,910	178,389	212,526
Development service fee income		82,673	12,941	0
Total operating revenue		719,778	710,698	773,960
OPERATING EXPENSE
Rental property		66,018	94,177	123,997
Real estate taxes		90,187	95,202	101,647
General and administrative		56,975	67,088	68,264
Expensed pursuit costs		5,066	1,016	605
Depreciation and amortization		175,137	196,705	217,864
Development service fee expense		85,805	12,165	0
Impairment - real estate assets		3,946	3,879	17,215
Total operating expense		483,134	470,232	529,592
Operating income		236,644	240,466	244,368
OTHER INCOME (EXPENSE)
Interest and other income		7,778	13,817	23,758
Loss on debt extinguishment		(49)	(27,099)	0
Interest expense		(88,857)	(112,299)	(133,557)
Total other income (expense)		(81,128)	(125,581)	(109,799)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures		155,516	114,885	134,569
Gain on property dispositions		100,387	219,270	100,314
Income taxes		(1,992)	(1,971)	(2,673)
Equity in earnings of unconsolidated joint ventures		17,155	21,970	3,149
Income from continuing operations		271,066	354,154	235,359
Discontinued operations (including net gain on property dispositions of $14,578 for the year ended December 31, 2017)		18,979	11,991	10,565
Net income		290,045	366,145	245,924
Noncontrolling interest – consolidated joint ventures		(481)	(258)	(249)
Preferred unit distributions		(472)	(472)	(472)
Income available to common shareholders		289,092	365,415	245,203
Comprehensive income attributable to common shareholders
Net income		290,045	366,145	245,924
Other comprehensive income (loss) - foreign currency translation		18,066	(34,744)	(12,540)
Other comprehensive income (loss) - derivative instruments		605	410	(488)
Other comprehensive loss		18,671	(34,334)	(13,028)
Total comprehensive income		$ 308,716	$ 331,811	$ 232,896
Weighted average number of common shares outstanding
Basic (shares)		150,270	149,740	151,783
Diluted (shares)		151,069	150,425	152,383
Net Income Allocated to General Partners		$ 282,340	$ 356,817	$ 239,483
Net Income Allocated to Limited Partners		7,224	9,070	6,192
Amounts attributable to common shareholders
Income from continuing operations		270,585	353,896	235,110
Income available to common shareholders		$ 289,092	$ 365,415	$ 245,203
Liberty Property Limited Partnership [Member] | Common units [Member]
Basic:
Income from continuing operations (USD per share/unit)		$ 1.79	$ 2.36	$ 1.55
Income from discontinued operations (USD per share/unit)		0.13	0.08	0.07
Income per common share - basic (USD per share/unit)		1.92	2.44	1.62
Diluted:
Income from continuing operations (USD per share/unit)		1.78	2.35	1.54
Income from discontinued operations (USD per share/unit)		0.13	0.08	0.07
Income per common share - diluted (USD per share/unit)		$ 1.91	$ 2.43	$ 1.61

[1] (1) Prior to the fourth quarter of 2016, development service fee income had been classified as other income and development service fee expense had been classified as general and administrative expense. See Note 2.