Liberty Property Limited Partnership 10-Q 3 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2015	Jul. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	LIBERTY PROPERTY TRUST
Entity Central Index Key	921,112
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		149,861,775
Liberty Property Limited Partnership [Member]
Entity Information [Line Items]
Entity Registrant Name	LIBERTY PROPERTY LIMITED PARTNERSHIP
Entity Central Index Key	921,113

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
ASSETS
Land and land improvements	$ 1,207,305	$ 1,189,760
Building and improvements	5,305,894	5,343,908
Less accumulated depreciation	(1,205,440)	(1,182,569)
Operating real estate	5,307,759	5,351,099
Development in progress	225,154	277,411
Land held for development	280,334	269,059
Net real estate	5,813,247	5,897,569
Cash and cash equivalents	73,053	69,346
Restricted cash	17,929	20,325
Accounts receivable	14,837	15,481
Deferred rent receivable	115,944	107,909
Deferred financing and leasing costs, net of accumulated amortization (2015, $176,671; 2014, $169,468)	200,782	206,286
Investments in and advances to unconsolidated joint ventures	215,715	208,832
Assets held for sale	0	8,389
Prepaid expenses and other assets	105,223	91,399
Total assets	6,556,730	6,625,536
LIABILITIES
Mortgage loans	481,621	487,301
Unsecured notes	2,608,089	2,509,094
Credit facility	70,000	167,000
Accounts payable	46,393	52,043
Accrued interest	27,176	24,513
Dividend and distributions payable	72,687	72,253
Other liabilities	197,960	219,418
Total liabilities	3,503,926	3,531,622
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2015 and December 31, 2014	7,537	7,537
EQUITY
Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 150,737,328 (includes 1,249,909 in treasury) and 149,807,179 (includes 1,249,909 in treasury) shares issued and outstanding as of June 30, 2015 and December 31, 2014, respectively	151	150
Additional paid-in capital	3,775,548	3,740,594
Accumulated other comprehensive loss	(4,863)	(6,252)
Distributions in excess of net income	(730,242)	(654,869)
Common shares in treasury, at cost, 1,249,909 shares as of June 30, 2015 and December 31, 2014	(51,951)	(51,951)
Total Liberty Property Trust shareholders' equity	2,988,643	3,027,672
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	52,705	54,786
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total equity	3,045,267	3,086,377
Total liabilities, noncontrolling interest - operating partnership and equity	6,556,730	6,625,536
Liberty Property Limited Partnership [Member]
ASSETS
Land and land improvements	1,207,305	1,189,760
Building and improvements	5,305,894	5,343,908
Less accumulated depreciation	(1,205,440)	(1,182,569)
Operating real estate	5,307,759	5,351,099
Development in progress	225,154	277,411
Land held for development	280,334	269,059
Net real estate	5,813,247	5,897,569
Cash and cash equivalents	73,053	69,346
Restricted cash	17,929	20,325
Accounts receivable	14,837	15,481
Deferred rent receivable	115,944	107,909
Deferred financing and leasing costs, net of accumulated amortization (2015, $176,671; 2014, $169,468)	200,782	206,286
Investments in and advances to unconsolidated joint ventures	215,715	208,832
Assets held for sale	0	8,389
Prepaid expenses and other assets	105,223	91,399
Total assets	6,556,730	6,625,536
LIABILITIES
Mortgage loans	481,621	487,301
Unsecured notes	2,608,089	2,509,094
Credit facility	70,000	167,000
Accounts payable	46,393	52,043
Accrued interest	27,176	24,513
Dividend and distributions payable	72,687	72,253
Other liabilities	197,960	219,418
Total liabilities	3,503,926	3,531,622
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2015 and December 31, 2014	7,537	7,537
EQUITY
General partner’s equity - 149,487,419 (net of 1,249,909 treasury units) and 148,557,270 (net of 1,249,909 treasury units) common units outstanding as of June 30, 2015 and December 31, 2014, respectively	2,988,643	3,027,672
Limited partners' equity	52,705	54,786
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total equity	3,045,267	3,086,377
Total liabilities, noncontrolling interest - operating partnership and equity	$ 6,556,730	$ 6,625,536

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Amortized Cost on Deferred Financing and Leasing Costs	$ 176,671,000	$ 169,468,000
Noncontrolling Interest Operating Partnership Common Units Outstanding	3,539,075	3,553,566
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares Authorized	283,987,000	283,987,000
Common Stock, Shares, Issued	150,737,328	149,807,179
Common Stock, Shares, Outstanding	150,737,328	149,807,179
Treasury Stock, Shares	1,249,909	1,249,909
Liberty Property Limited Partnership [Member]
Amortized Cost on Deferred Financing and Leasing Costs	$ 176,671,000	$ 169,468,000
Limited Partners' Capital Account, Units Outstanding	3,539,075	3,553,566
Common Stock, Shares, Outstanding	149,487,419	148,557,270
Treasury Stock, Shares	1,249,909	1,249,909
Series I 2 [Member]
Temporary Equity, Shares Outstanding	301,483	301,483
Series I 2 [Member] | Liberty Property Limited Partnership [Member]
Temporary Equity, Shares Outstanding	301,483	301,483

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
OPERATING REVENUE
Rental	$ 147,367	$ 139,377	$ 295,952	$ 278,326
Operating expense reimbursement	56,151	53,583	114,467	112,264
Total operating revenue	203,518	192,960	410,419	390,590
OPERATING EXPENSE
Rental property	31,949	31,982	67,520	70,623
Real estate taxes	26,462	25,716	52,626	50,217
General and administrative	17,053	14,973	35,855	33,329
Depreciation and amortization	56,833	57,872	115,629	114,606
Impairment - real estate assets	1,036	0	16,775	0
Total operating expenses	133,333	130,543	288,405	268,775
Operating income	70,185	62,417	122,014	121,815
OTHER INCOME (EXPENSE)
Other income	6,581	3,115	12,952	5,553
Interest expense	(35,066)	(38,470)	(69,736)	(77,677)
Total other income (expense)	(28,485)	(35,355)	(56,784)	(72,124)
Income before gain on property dispositions, income taxes and equity in (loss) earnings of unconsolidated joint ventures	41,700	27,062	65,230	49,691
Gain on property dispositions	1,249	1,897	3,520	1,898
Income taxes	(1,169)	(693)	(2,014)	(1,224)
Equity in (loss) earnings of unconsolidated joint ventures	(5,254)	1,546	1,652	5,705
Income from continuing operations	36,526	29,812	68,388	56,070
Discontinued operations (including net gain on property dispositions of $139 for the three months ended June 30, 2014 and $46,254 for the six months ended June 30, 2014)	0	295	0	48,143
Net income	36,526	30,107	68,388	104,213
Noncontrolling interest – operating partnership	(958)	(821)	(1,811)	(2,674)
Noncontrolling interest - consolidated joint ventures	(55)	(37)	(113)	(390)
Net income available to common shareholders	35,513	29,249	66,464	101,149
Comprehensive income attributable to common shareholders
Net income	36,526	30,107	68,388	104,213
Other comprehensive income - foreign currency translation	12,151	6,464	1,741	7,811
Other comprehensive income (loss) - derivative instruments	628	(1,145)	(319)	(1,656)
Other comprehensive income	12,779	5,319	1,422	6,155
Total comprehensive income	49,305	35,426	69,810	110,368
Less: comprehensive income attributable to noncontrolling interest	(1,309)	(983)	(1,957)	(3,209)
Comprehensive income attributable to common shareholders	$ 47,996	$ 34,443	$ 67,853	$ 107,159
Weighted average number of common shares outstanding
Basic	148,778	147,012	148,574	146,749
Diluted	149,454	147,774	149,247	147,444
Amounts attributable to common shareholders
Income from continuing operations	$ 35,513	$ 28,961	$ 66,464	$ 54,137
Discontinued operations	0	288	0	47,012
Net income available to common shareholders	35,513	29,249	66,464	101,149
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	147,367	139,377	295,952	278,326
Operating expense reimbursement	56,151	53,583	114,467	112,264
Total operating revenue	203,518	192,960	410,419	390,590
OPERATING EXPENSE
Rental property	31,949	31,982	67,520	70,623
Real estate taxes	26,462	25,716	52,626	50,217
General and administrative	17,053	14,973	35,855	33,329
Depreciation and amortization	56,833	57,872	115,629	114,606
Impairment - real estate assets	1,036	0	16,775	0
Total operating expenses	133,333	130,543	288,405	268,775
Operating income	70,185	62,417	122,014	121,815
OTHER INCOME (EXPENSE)
Other income	6,581	3,115	12,952	5,553
Interest expense	(35,066)	(38,470)	(69,736)	(77,677)
Total other income (expense)	(28,485)	(35,355)	(56,784)	(72,124)
Income before gain on property dispositions, income taxes and equity in (loss) earnings of unconsolidated joint ventures	41,700	27,062	65,230	49,691
Gain on property dispositions	1,249	1,897	3,520	1,898
Income taxes	(1,169)	(693)	(2,014)	(1,224)
Equity in (loss) earnings of unconsolidated joint ventures	(5,254)	1,546	1,652	5,705
Income from continuing operations	36,526	29,812	68,388	56,070
Discontinued operations (including net gain on property dispositions of $139 for the three months ended June 30, 2014 and $46,254 for the six months ended June 30, 2014)	0	295	0	48,143
Net income	36,526	30,107	68,388	104,213
Noncontrolling interest - consolidated joint ventures	(55)	(37)	(113)	(390)
Preferred unit distributions	(118)	(118)	(236)	(236)
Net income available to common shareholders	36,353	29,952	68,039	103,587
Comprehensive income attributable to common shareholders
Net income	36,526	30,107	68,388	104,213
Other comprehensive income - foreign currency translation	12,151	6,464	1,741	7,811
Other comprehensive income (loss) - derivative instruments	628	(1,145)	(319)	(1,656)
Other comprehensive income	12,779	5,319	1,422	6,155
Total comprehensive income	$ 49,305	$ 35,426	$ 69,810	$ 110,368
Weighted average number of common shares outstanding
Basic	152,317	150,563	152,114	150,304
Diluted	152,993	151,325	152,787	150,999
Net income allocated to general partners	$ 35,513	$ 29,249	$ 66,464	$ 101,149
Net income allocated to limited partners	958	821	1,811	2,674
Amounts attributable to common shareholders
Income from continuing operations	36,471	29,775	68,275	55,680
Net income available to common shareholders	$ 36,353	$ 29,952	$ 68,039	$ 103,587
Common shares [Member]
Basic:
Income from continuing operations	$ 0.24	$ 0.20	$ 0.45	$ 0.37
Income from discontinued operations	0	0	0	0.32
Income per common share - basic	0.24	0.20	0.45	0.69
Diluted:
Income from continuing operations	0.24	0.20	0.45	0.37
Income from discontinued operations	0	0	0	0.32
Income per common share - diluted	0.24	0.20	0.45	0.69
Distributions per common share or unit	0.475	0.475	0.95	0.95
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income from continuing operations	0.24	0.20	0.45	0.37
Income from discontinued operations	0	0	0	0.32
Income per common share - basic	0.24	0.20	0.45	0.69
Diluted:
Income from continuing operations	0.24	0.20	0.45	0.37
Income from discontinued operations	0	0	0	0.32
Income per common share - diluted	0.24	0.20	0.45	0.69
Distributions per common share or unit	$ 0.475	$ 0.475	$ 0.95	$ 0.95

Income Statement Parenthetical

Income Statement Parenthetical (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Gain on property dispositions	$ 0	$ 139	$ 0	$ 46,254
Liberty Property Limited Partnership [Member]
Gain on property dispositions	$ 0	$ 139	$ 0	$ 46,254

Consolidated Statement of Equit

Consolidated Statement of Equity - 6 months ended Jun. 30, 2015 - USD ($)	Total	Common Shares Of Beneficial Interest [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Distributions in Excess of Net Income [Member]	Common Shares Held in Treasury [Member]	Total Liberty Property Trust Shareholders' Equity [Member]	Noncontrolling interest operating partnership-Common [Member]	Noncontrolling interest-consolidated joint ventures [Member]	Total Equity [Member]	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member]General Partners Equity [Member]	Liberty Property Limited Partnership [Member]Noncontrolling interest operating partnership-Common [Member]	Liberty Property Limited Partnership [Member]Noncontrolling interest-consolidated joint ventures [Member]	Liberty Property Limited Partnership [Member]Total Equity [Member]
Beginning Balance at Dec. 31, 2014	$ 3,086,377,000	$ 150,000	$ 3,740,594,000	$ (6,252,000)	$ (654,869,000)	$ (51,951,000)	$ 3,027,672,000	$ 54,786,000	$ 3,919,000	$ 3,086,377,000	$ 3,086,377,000	$ 3,027,672,000	$ 54,786,000	$ 3,919,000	$ 3,086,377,000
Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance at Dec. 31, 2014	7,537,000										7,537,000
Net proceeds from the issuance of common shares		1,000	25,226,000				25,227,000			25,227,000
Net income	68,388,000				66,464,000		66,464,000	1,575,000	113,000	68,152,000	68,388,000	66,464,000	1,575,000	113,000	68,152,000
Net income (Mezzanine)	236,000										236,000
Distributions (Mezzanine)	(236,000)										(236,000)
Redemption of limited partners common units for common shares			224,000				224,000	(224,000)		0		224,000	(224,000)		0
Contributions from partners												34,731,000			34,731,000
Distributions					(141,837,000)		(141,837,000)	(3,465,000)	(113,000)	(145,415,000)
Distributions to partners												(141,837,000)	(3,465,000)	(113,000)	(145,415,000)
Share-based compensation			9,504,000				9,504,000			9,504,000
Other comprehensive income - foreign currency translation	1,741,000			1,701,000			1,701,000	40,000		1,741,000	1,741,000	1,701,000	40,000		1,741,000
Other comprehensive loss - derivative instruments	(319,000)			(312,000)			(312,000)	(7,000)		(319,000)	(319,000)	(312,000)	(7,000)		(319,000)
Ending Balance at Jun. 30, 2015	3,045,267,000	$ 151,000	$ 3,775,548,000	$ (4,863,000)	$ (730,242,000)	$ (51,951,000)	$ 2,988,643,000	$ 52,705,000	$ 3,919,000	$ 3,045,267,000	3,045,267,000	$ 2,988,643,000	$ 52,705,000	$ 3,919,000	$ 3,045,267,000
Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance at Jun. 30, 2015	$ 7,537,000										$ 7,537,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
OPERATING ACTIVITIES
Net income	$ 68,388	$ 104,213
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	117,160	116,547
Amortization of deferred financing costs	2,168	2,629
Impairment - real estate assets	16,775	0
Equity in earnings of unconsolidated joint ventures	(1,652)	(5,705)
Distributions from unconsolidated joint ventures	4,441	0
Gain on property dispositions	(3,520)	(48,152)
Share-based compensation/Non-cash compensation	9,504	8,500
Other	(6,750)	(2,210)
Changes in operating assets and liabilities:
Restricted cash	2,541	33,239
Accounts receivable	665	(1,307)
Deferred rent receivable	(11,319)	(7,548)
Prepaid expenses and other assets	(16,540)	(29,907)
Accounts payable	(5,647)	9,100
Accrued interest	2,663	2,753
Other liabilities	(5,780)	(34,802)
Net cash provided by operating activities	173,097	147,350
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(36,714)	(90,837)
Investment in operating properties - other	(33,585)	(39,073)
Investments in and advances to unconsolidated joint ventures	(17,182)	(12,008)
Distributions from unconsolidated joint ventures	7,979	5,429
Net proceeds from disposition of properties/land	156,891	351,299
Investment in development in progress	(78,120)	(150,199)
Investment in land held for development	(23,150)	(12,793)
Investment in deferred leasing costs	(23,395)	(18,252)
Other	5,154	5,627
Net cash (used in) provided by investing activities	(42,122)	39,193
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	25,227	31,588
Proceeds from unsecured notes	398,576	0
Repayment of unsecured notes	(300,000)	0
Repayments of mortgage loans	(4,567)	(7,013)
Proceeds from credit facility	613,200	0
Repayments on credit facility	(710,200)	0
Payment of deferred financing costs	(3,551)	(3,635)
Distribution paid on common shares	(141,395)	(139,598)
Distribution paid on units	(3,821)	(3,814)
Net cash used in financing activities	(126,531)	(122,472)
Net increase in cash and cash equivalents	4,444	64,071
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(737)	1,193
Cash and cash equivalents at beginning of period	69,346	163,414
Cash and cash equivalents at end of period	73,053	228,678
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	68,388	104,213
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	117,160	116,547
Amortization of deferred financing costs	2,168	2,629
Impairment - real estate assets	16,775	0
Equity in earnings of unconsolidated joint ventures	(1,652)	(5,705)
Distributions from unconsolidated joint ventures	4,441	0
Gain on property dispositions	(3,520)	(48,152)
Share-based compensation/Non-cash compensation	9,504	8,500
Other	(6,750)	(2,210)
Changes in operating assets and liabilities:
Restricted cash	2,541	33,239
Accounts receivable	665	(1,307)
Deferred rent receivable	(11,319)	(7,548)
Prepaid expenses and other assets	(16,540)	(29,907)
Accounts payable	(5,647)	9,100
Accrued interest	2,663	2,753
Other liabilities	(5,780)	(34,802)
Net cash provided by operating activities	173,097	147,350
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(36,714)	(90,837)
Investment in operating properties - other	(33,585)	(39,073)
Investments in and advances to unconsolidated joint ventures	(17,182)	(12,008)
Distributions from unconsolidated joint ventures	7,979	5,429
Net proceeds from disposition of properties/land	156,891	351,299
Investment in development in progress	(78,120)	(150,199)
Investment in land held for development	(23,150)	(12,793)
Investment in deferred leasing costs	(23,395)	(18,252)
Other	5,154	5,627
Net cash (used in) provided by investing activities	(42,122)	39,193
FINANCING ACTIVITIES
Proceeds from unsecured notes	398,576	0
Repayment of unsecured notes	(300,000)	0
Repayments of mortgage loans	(4,567)	(7,013)
Proceeds from credit facility	613,200	0
Repayments on credit facility	(710,200)	0
Payment of deferred financing costs	(3,551)	(3,635)
Capital contributions	25,227	31,588
Distributions to partners	(145,216)	(143,412)
Net cash used in financing activities	(126,531)	(122,472)
Net increase in cash and cash equivalents	4,444	64,071
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(737)	1,193
Cash and cash equivalents at beginning of period	69,346	163,414
Cash and cash equivalents at end of period	$ 73,053	$ 228,678

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Organization and Basis of Presentation Organization Liberty Property Trust (the “Trust”) is a self-administered and self-managed Maryland real estate investment trust (a “REIT”). Substantially all of the Trust’s assets are owned directly or indirectly, and substantially all of the Trust’s operations are conducted directly or indirectly, by its subsidiary, Liberty Property Limited Partnership, a Pennsylvania limited partnership (the “Operating Partnership” and, together with the Trust and their consolidated subsidiaries, the “Company”). The Trust is the sole general partner and also a limited partner of the Operating Partnership, owning 97.7% of the common equity of the Operating Partnership at June 30, 2015 . The Company owns and operates industrial properties nationally and owns and operates office properties in a focused group of office markets. Additionally, the Company owns certain assets in the United Kingdom. Unless otherwise indicated, the notes to the Consolidated Financial Statements apply to both the Trust and the Operating Partnership. The terms the “Company,” “we,” “our” and “us” mean the Trust and Operating Partnership collectively. Basis of Presentation The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with United States generally accepted accounting principles (“US GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements and should be read in conjunction with the consolidated financial statements and notes thereto included in the Annual Report on Form 10-K of the Company for the year ended December 31, 2014 . In the opinion of management, all adjustments (consisting solely of normal recurring adjustments) necessary for a fair presentation of the financial statements for these interim periods have been included. The results of interim periods are not necessarily indicative of the results to be obtained for a full fiscal year. Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which supersedes nearly all existing revenue recognition guidance. The standard clarifies the required factors that an entity must consider when recognizing revenue. The standard also requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company is evaluating the impact ASU 2014-09 will have on its financial position and results of operations. In April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The standard requires the costs for issuing debt to appear on a balance sheet as a direct deduction from the debt's value. ASU 2015-03 is effective for the Company beginning January 1, 2016. The standard would be applied retrospectively. The Company does not anticipate that the adoption of ASU 2015-03 will have a material impact on its financial position or results of operations.

Income per Common Share of the

Income per Common Share of the Trust	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Income per Common Share of the Trust The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 148,778 $ 0.24 $ 28,961 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 149,454 $ 0.24 $ 28,961 147,774 $ 0.20 Basic income from discontinued operations Discontinued operations net of noncontrolling interest $ — 148,778 $ — $ 288 147,012 $ — Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest $ — 149,454 $ — $ 288 147,774 $ — Basic income per common share Net income available to common shareholders $ 35,513 148,778 $ 0.24 $ 29,249 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income per common share Net income available to common shareholders $ 35,513 149,454 $ 0.24 $ 29,249 147,774 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 66,464 148,574 $ 0.45 $ 54,137 146,749 $ 0.37 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest 66,464 149,247 $ 0.45 54,137 147,444 $ 0.37 Basic income from discontinued operations Discontinued operations net of noncontrolling interest — 148,574 $ — 47,012 146,749 $ 0.32 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest — 149,247 $ — 47,012 147,444 $ 0.32 Basic income per common share Net income available to common shareholders 66,464 148,574 $ 0.45 101,149 146,749 $ 0.69 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income per common share Net income available to common shareholders $ 66,464 149,247 $ 0.45 $ 101,149 147,444 $ 0.69 Dilutive shares for long-term compensation plans represent the unvested common shares outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common share for the three and six months ended June 30, 2015 was 1,528,000 and 1,448,000 , respectively, as compared to 750,000 for both the three and six month periods in 2014 .
Stock Option Exercises [Text Block]	During the three and six months ended June 30, 2015 , 8,000 and 53,000 common shares, respectively, were issued upon the exercise of options. During the year ended December 31, 2014 , 44,000 common shares were issued upon the exercise of options.

Income per Common Unit of the O

Income per Common Unit of the Operating Partnership	6 Months Ended
	Jun. 30, 2015
Earnings Per Share, Basic and Diluted [Line Items]
Earnings Per Share [Text Block]	Income per Common Share of the Trust The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 148,778 $ 0.24 $ 28,961 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 149,454 $ 0.24 $ 28,961 147,774 $ 0.20 Basic income from discontinued operations Discontinued operations net of noncontrolling interest $ — 148,778 $ — $ 288 147,012 $ — Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest $ — 149,454 $ — $ 288 147,774 $ — Basic income per common share Net income available to common shareholders $ 35,513 148,778 $ 0.24 $ 29,249 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income per common share Net income available to common shareholders $ 35,513 149,454 $ 0.24 $ 29,249 147,774 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 66,464 148,574 $ 0.45 $ 54,137 146,749 $ 0.37 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest 66,464 149,247 $ 0.45 54,137 147,444 $ 0.37 Basic income from discontinued operations Discontinued operations net of noncontrolling interest — 148,574 $ — 47,012 146,749 $ 0.32 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest — 149,247 $ — 47,012 147,444 $ 0.32 Basic income per common share Net income available to common shareholders 66,464 148,574 $ 0.45 101,149 146,749 $ 0.69 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income per common share Net income available to common shareholders $ 66,464 149,247 $ 0.45 $ 101,149 147,444 $ 0.69 Dilutive shares for long-term compensation plans represent the unvested common shares outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common share for the three and six months ended June 30, 2015 was 1,528,000 and 1,448,000 , respectively, as compared to 750,000 for both the three and six month periods in 2014 .
Stock Option Exercises [Text Block]	During the three and six months ended June 30, 2015 , 8,000 and 53,000 common shares, respectively, were issued upon the exercise of options. During the year ended December 31, 2014 , 44,000 common shares were issued upon the exercise of options.
Liberty Property Limited Partnership [Member]
Earnings Per Share, Basic and Diluted [Line Items]
Earnings Per Share [Text Block]	Income per Common Unit of the Operating Partnership The following table sets forth the computation of basic and diluted income per common unit of the Operating Partnership (in thousands, except per unit amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income from continuing operations - net of noncontrolling interest - consolidated joint ventures $ 36,471 $ 29,775 Less: Preferred unit distributions (118 ) (118 ) Basic income from continuing operations Income from continuing operations available to common unitholders $ 36,353 152,317 $ 0.24 $ 29,657 150,563 $ 0.20 Dilutive units for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations available to common unitholders $ 36,353 152,993 $ 0.24 $ 29,657 151,325 $ 0.20 Basic income from discontinued operations Discontinued operations $ — 152,317 $ — $ 295 150,563 $ — Dilutive units for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations $ — 152,993 $ — $ 295 151,325 $ — Basic income per common unit Income available to common unitholders $ 36,353 152,317 $ 0.24 $ 29,952 150,563 $ 0.20 Dilutive units for long-term compensation plans — 676 — 762 Diluted income per common unit Income available to common unitholders $ 36,353 152,993 $ 0.24 $ 29,952 151,325 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income from continuing operations net of noncontrolling interest - consolidated joint ventures $ 68,275 $ 55,680 Less: Preferred unit distributions (236 ) (236 ) Basic income from continuing operations Income from continuing operations available to common unitholders 68,039 152,114 $ 0.45 55,444 150,304 $ 0.37 Dilutive units for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations available to common unitholders 68,039 152,787 $ 0.45 55,444 150,999 $ 0.37 Basic income from discontinued operations Discontinued operations — 152,114 $ — 48,143 150,304 $ 0.32 Dilutive units for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations — 152,787 $ — 48,143 150,999 $ 0.32 Basic income per common unit Income available to common unitholders 68,039 152,114 $ 0.45 103,587 150,304 $ 0.69 Dilutive units for long-term compensation plans — 673 — 695 Diluted income per common unit Income available to common unitholders $ 68,039 152,787 $ 0.45 $ 103,587 150,999 $ 0.69 Dilutive units for long-term compensation plans represent the unvested common units outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common unit for the three and six months ended June 30, 2015 was 1,528,000 and 1,448,000 , respectively, as compared to 750,000 for both the three and six month periods in 2014 .
Stock Option Exercises [Text Block]	During the three and six months ended June 30, 2015 , 8,000 and 53,000 common units, respectively, were issued upon exercise of options. During the year ended December 31, 2014 , 44,000 common units were issued upon the exercise of options.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Income (Loss) The following table sets forth the components of Accumulated Other Comprehensive Income (Loss) (in thousands): Six Months Ended June 30, 2015 2014 Foreign Currency Translation: Beginning balance $ (5,823 ) $ 8,592 Translation adjustment 1,741 7,811 Ending balance (4,082 ) 16,403 Derivative Instruments: Beginning balance (377 ) 1,584 Unrealized loss (1,022 ) (2,382 ) Reclassification adjustment (1) 703 726 Ending balance (696 ) (72 ) Total accumulated other comprehensive (loss) income (4,778 ) 16,331 Less: portion included in noncontrolling interest – operating partnership (85 ) (579 ) Total accumulated other comprehensive (loss) income included in shareholders' equity/owners' equity $ (4,863 ) $ 15,752 (1) Amounts reclassified out of Accumulated Other Comprehensive (Loss) Income/General & Limited Partner's Equity into contractual interest expense.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2015
Segment Reporting, Measurement Disclosures [Abstract]
Segment Information	Segment Information The Company owns and operates industrial properties nationally and owns and operates office properties in a focused group of office markets. Additionally, the Company owns certain assets in the United Kingdom. The Company's reportable segments are as follows. • Carolinas; • Chicago/Milwaukee; • Houston; • Lehigh/Central PA; • Minnesota; • Orlando; • Philadelphia; • Richmond/Hampton Roads; • Southeastern PA; • South Florida; • Tampa; • United Kingdom. Certain other segments are aggregated into an "Other" category which includes the reportable segments: Arizona; Atlanta; Cincinnati/Columbus/Indianapolis; Dallas; Maryland; New Jersey; Northern Virginia; Southern California; Washington D.C. and other. The Company evaluates the performance of its reportable segments based on net operating income. Net operating income includes operating revenue from external customers, real estate taxes, amortization of lease transaction costs and other operating expenses which relate directly to the management and operation of the assets within each reportable segment. The Company's accounting policies for the segments are the same as those used in the Company's consolidated financial statements. There are no material inter-segment transactions. The operating information by reportable segment is as follows (in thousands): For the Three Months For the Six Months Ended June 30, Ended June 30, 2015 2014 2015 2014 Operating revenue Carolinas $ 10,062 $ 8,486 $ 19,906 $ 16,803 Chicago/Milwaukee 8,931 8,152 18,724 16,723 Houston 13,151 12,128 25,474 23,995 Lehigh/Central PA 32,844 28,195 66,398 57,819 Minnesota 12,276 13,541 24,948 27,292 Orlando 5,409 8,061 10,674 16,056 Philadelphia 9,889 8,691 19,871 18,099 Richmond/Hampton Roads 10,150 10,115 20,641 20,184 South Florida 12,378 11,707 24,585 24,016 Southeastern PA 38,473 36,309 77,712 74,746 Tampa 13,637 13,230 27,099 26,404 United Kingdom 3,965 4,218 7,690 8,320 Other 32,439 30,122 66,834 65,158 Segment-level operating revenue 203,604 192,955 410,556 395,615 Reconciliation to total operating revenues Discontinued operations — 29 — (4,719 ) Other (86 ) (24 ) (137 ) (306 ) Total operating revenue $ 203,518 $ 192,960 $ 410,419 $ 390,590 Net operating income Carolinas $ 7,066 $ 5,693 $ 13,684 $ 11,435 Chicago/Milwaukee 6,125 4,973 12,868 10,136 Houston 7,689 7,232 14,910 14,284 Lehigh/Central PA 23,647 19,773 46,618 39,013 Minnesota 5,149 6,770 11,134 13,390 Orlando 3,685 5,354 7,256 10,846 Philadelphia 7,310 6,790 14,332 13,511 Richmond/Hampton Roads 6,295 6,054 12,524 11,973 South Florida 7,149 6,891 13,978 14,418 Southeastern PA 21,426 20,060 42,414 39,660 Tampa 8,625 8,488 17,327 16,929 United Kingdom 2,782 2,722 5,298 5,572 Other 21,516 19,167 44,387 40,898 Segment-level net operating income 128,464 119,967 256,730 242,065 Reconciliation to income from continuing operations Interest expense (1) (35,066 ) (38,470 ) (69,736 ) (78,234 ) Depreciation/amortization expense (1) (2) (41,772 ) (44,561 ) (85,281 ) (89,098 ) Impairment - real estate assets (1,036 ) — (16,775 ) — Gain on property dispositions 1,249 1,897 3,520 1,898 Equity in (loss) earnings of unconsolidated joint ventures (5,254 ) 1,546 1,652 5,705 General and administrative expense (1) (2) (9,128 ) (8,232 ) (19,437 ) (20,633 ) Discontinued operations excluding interest and gain on property dispositions — (156 ) — (2,446 ) Income taxes (2) (1,051 ) (663 ) (1,757 ) (1,146 ) Other 120 (1,516 ) (528 ) (2,041 ) Income from continuing operations $ 36,526 $ 29,812 $ 68,388 $ 56,070 (1) Includes activity on discontinued operations. (2) Excludes costs which are included in determining segment-level net operating income. During the three and six months ended June 30, 2015 , the Company acquired one property comprising 410,000 square feet for $36.7 million in the Company's Southern California segment. The Company's sales by reportable segment for the three and six months ended June 30, 2015 are as follows: Three months ended June 30, 2015 Six months ended June 30, 2015 Properties Sold Square Feet (000s) Proceeds (000s) Properties Sold Square Feet (000s) Proceeds (000s) Minnesota 1 87 $ 5,800 1 87 $ 5,800 Richmond/Hampton Roads 22 1,319 110,300 (1) 22 1,319 110,300 (1) Southeastern PA — — — 1 83 8,720 Other — — — 6 539 33,512 Total 23 1,406 $ 116,100 30 2,028 $ 158,332 (1) Includes proceeds from the sale of 3.1 acres of land. During the three and six months ended June 30, 2015 , the Company sold 22 properties and 3.1 acres of land in the Richmond/Hampton Roads segment for $110.3 million to a firm controlled by the brother of David L. Lingerfelt, a member of the Company's Board of Trustees. The Company's total assets by reportable segment as of June 30, 2015 and December 31, 2014 is as follows (in thousands): June 30, 2015 December 31, 2014 Total assets Carolinas $ 329,705 $ 325,690 Chicago/Milwaukee 425,320 422,531 Houston 424,481 418,154 Lehigh/Central PA 1,046,162 1,023,641 Minnesota 330,856 333,506 Orlando 162,167 160,899 Philadelphia 390,707 366,577 Richmond/Hampton Roads 124,246 250,205 South Florida 410,717 400,034 Southeastern PA 675,774 698,163 Tampa 332,784 335,652 United Kingdom 228,624 231,276 Other 1,566,591 1,553,250 Segment-level total assets 6,448,134 6,519,578 Corporate Other 108,596 105,958 Total assets $ 6,556,730 $ 6,625,536

Accounting for the Impairment o

Accounting for the Impairment or Disposal of Long-Lived Assets	6 Months Ended
	Jun. 30, 2015
Disposal Group, Including Discontinued Operation, Long Lived Assets [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Accounting for the Impairment or Disposal of Long-Lived Assets Prior to the adoption of Accounting Standards Update (ASU) 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360), Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-08") on January 1, 2014, the results of operations for all operating properties sold or held for sale during the reported periods were shown under discontinued operations on the consolidated statements of comprehensive income. Under ASU 2014-08, operating properties that were sold or classified as held for sale before the adoption of ASU 2014-08 continue to be classified as discontinued operations. Accordingly, operating properties previously reported as discontinued operations will continue to be presented as discontinued operations on the consolidated statements of comprehensive income for all periods presented. A summary of the results of operations for the properties classified as discontinued operations through the respective disposition dates is as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Revenues $ — $ (29 ) $ — $ 4,719 Operating expenses — 183 — (2,312 ) Interest and other income — 2 — 39 Interest expense — — — (557 ) Depreciation and amortization — — — — Income before gain on property dispositions — 156 — 1,889 Gain on property dispositions — 139 — 46,254 Net income $ — $ 295 $ — $ 48,143 Interest expense has been allocated to discontinued operations. The allocation of interest expense to discontinued operations was based on the ratio of net assets sold and held for sale (without continuing involvement) to the sum of total net assets plus consolidated debt.
Asset Impairment Charges [Text Block]	Asset Impairment The Company disposes of and anticipates the potential disposition of certain properties prior to the end of their remaining useful lives. During the three months ended June 30, 2015 , the Company recognized $1.0 million in impairments which related to the Company's Maryland segment. During the six months ended June 30, 2015 , the Company recognized $16.8 million in impairments, $13.4 million of which related to properties sold in the Company's Richmond/Hampton Roads reportable segment (see Note 5), $2.3 million of which related to the Company's Southeastern Pennsylvania reportable segment and $1.0 million of which related to the Company's Maryland segment. The Company determined these impairments based on third party offer prices and quoted offer prices for comparable transactions which are Level 2 and Level 3 inputs, respectively, according to the fair value hierarchy established by the FASB in Topic 820, "Fair Value Measurements and Disclosures." The Company has evaluated each of its properties and land held for development and has determined that there were no additional valuation adjustments necessary at June 30, 2015 . There were no impairments recognized during the three and six months ended June 30, 2014 .

Noncontrolling Interests of the

Noncontrolling Interests of the Trust	6 Months Ended
	Jun. 30, 2015
Stockholders' Equity Attributable to Noncontrolling Interest [Abstract]
Noncontrolling Interests	Noncontrolling Interests of the Trust Noncontrolling interests in the accompanying financial statements represent the interests of the common and preferred units in the Operating Partnership not held by the Trust. In addition, noncontrolling interests include third-party ownership interests in consolidated joint venture investments. Common units The common units outstanding have the same economic characteristics as common shares of the Trust. The 3,539,075 outstanding common units as of June 30, 2015 not held by the Trust share proportionately in the net income or loss and in any distributions of the Operating Partnership. The common units of the Operating Partnership not held by the Trust are redeemable at any time at the option of the holder. The Trust, as the sole general partner of the Operating Partnership, may at its option elect to settle the redemption in cash or through the exchange on a one-for-one basis of unregistered common shares of the Trust. The market value of the 3,539,075 outstanding common units based on the closing price of the common shares of the Trust at June 30, 2015 was $ 114.0 million .

Limited Partners' Equity of the

Limited Partners' Equity of the Operating Partnership	6 Months Ended
	Jun. 30, 2015
Preferred Units [Line Items]
Noncontrolling Interest Disclosure [Text Block]	Noncontrolling Interests of the Trust Noncontrolling interests in the accompanying financial statements represent the interests of the common and preferred units in the Operating Partnership not held by the Trust. In addition, noncontrolling interests include third-party ownership interests in consolidated joint venture investments. Common units The common units outstanding have the same economic characteristics as common shares of the Trust. The 3,539,075 outstanding common units as of June 30, 2015 not held by the Trust share proportionately in the net income or loss and in any distributions of the Operating Partnership. The common units of the Operating Partnership not held by the Trust are redeemable at any time at the option of the holder. The Trust, as the sole general partner of the Operating Partnership, may at its option elect to settle the redemption in cash or through the exchange on a one-for-one basis of unregistered common shares of the Trust. The market value of the 3,539,075 outstanding common units based on the closing price of the common shares of the Trust at June 30, 2015 was $ 114.0 million .
Liberty Property Limited Partnership [Member]
Preferred Units [Line Items]
Noncontrolling Interest Disclosure [Text Block]	Limited Partners' Equity and Noncontrolling Interest of the Operating Partnership Limited partners' equity in the accompanying financial statements represents the interests of the common and preferred units in the Operating Partnership not held by the Trust. The Operating Partnership's noncontrolling interest includes third-party ownership interests in consolidated joint venture investments. Common units The common units outstanding have the same economic characteristics as common shares of the Trust. The 3,539,075 outstanding common units as of June 30, 2015 not held by the Trust are the limited partners' equity - common units held by persons and entities other than the Trust. The common units of the Operating Partnership not held by the Trust are redeemable at any time at the option of the holder. The Trust, as the sole general partner of the Operating Partnership, may at its option elect to settle the redemption in cash or through the exchange on a one-for-one basis of unregistered common shares of the Trust. The market value of the 3,539,075 outstanding common units at June 30, 2015 based on the closing price of the common shares of the Trust at June 30, 2015 was $ 114.0 million .

Noncontrolling Interest - Opera

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units	6 Months Ended
	Jun. 30, 2015
Temporary Equity [Line Items]
Stockholders' Equity Note Disclosure [Text Block]	Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units As of June 30, 2015 , the Company had outstanding the following cumulative preferred units of the Operating Partnership: ISSUE AMOUNT UNITS LIQUIDATION PREFERENCE DIVIDEND RATE (in 000’s) Series I-2 $ 7,537 301 $25 6.25 % The preferred units are putable at the holder's option at any time and are callable at the Operating Partnership's option after a stated period of time for cash.

Indebtedness

Indebtedness	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Indebtedness In March 2015, the Company used proceeds from its unsecured credit facility together with available cash on hand to repay all $300 million of its 5.125% senior unsecured notes due March 2015. In March 2015, the Company issued $400 million of 3.75% senior unsecured notes due 2025. The net proceeds from this issuance were used to repay borrowings under the Company's unsecured credit facility and for general corporate purposes.

Disclosure of Fair Value of Fin

Disclosure of Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2015
Debt Instrument, Fair Value Disclosure [Abstract]
Disclosure of Fair Value of Financial Instruments	Disclosure of Fair Value of Financial Instruments The following disclosure of estimated fair value was determined by management using available market information and appropriate valuation methodologies. However, considerable judgment is necessary to interpret market data and develop estimated fair value. Accordingly, the following estimates are not necessarily indicative of the amounts the Company could have realized on disposition of the financial instruments at June 30, 2015 and December 31, 2014 . The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. The carrying value of cash and cash equivalents, restricted cash, accounts receivable, accounts payable, accrued interest, dividend and distributions payable and other liabilities are reasonable estimates of fair value because of the short-term nature of these instruments. The carrying value of the outstanding amounts under the Company's credit facility is a reasonable estimate of fair value because interest rates float at a rate based on LIBOR. The Company determines the fair value of its interest rate swaps by using the standard methodology of netting discounted future fixed cash payments with the discounted expected variable cash receipts. These variable cash receipts of interest rate swaps are based on expectations of future LIBOR interest rates (forward curves) estimated by observing market LIBOR interest rate curves. This is a Level 2 fair value calculation. Also, credit valuation adjustments are factored into the fair value calculations to account for potential nonperformance risk. These credit valuation adjustments were concluded to be not significant inputs for the fair value calculations for the periods presented. See Note 13 - Derivative Instruments. The Company used a discounted cash flow model to determine the estimated fair value of its debt as of June 30, 2015 . This is a Level 3 fair value calculation. The inputs used in preparing the discounted cash flow model include actual maturity dates and scheduled cash flows as well as estimates for market value discount rates. The Company updates the discounted cash flow model on a quarterly basis to reflect any changes in the Company's debt holdings and changes to discount rate assumptions. The following summarizes the fair value of the Company's mortgage loans and unsecured notes as of December 31, 2014 and June 30, 2015 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2014 $ 487,301 $ 501,231 $ 2,509,094 $ 2,704,069 As of June 30, 2015 $ 481,621 $ 494,561 $ 2,608,089 $ 2,639,474

Unconsolidated Joint Ventures

Unconsolidated Joint Ventures	6 Months Ended
	Jun. 30, 2015
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Unconsolidated Joint Ventures Liberty Washington, LP During the three and six months ended June 30, 2015, Liberty Washington LP (a joint venture in which the Company holds a 25% interest) recognized an impairment charge, the Company's share of which was $7.6 million . The impairment charge was related to the Company's Northern Virginia reportable segment and the Company's share was included in equity in earnings of unconsolidated joint ventures in the accompanying consolidated statements of comprehensive income. The Company determined this impairment based on third party offer prices. This is a Level 2 fair value calculation. Comcast Innovation and Technology Center The Company has entered into two joint ventures for the purpose of developing and owning the Comcast Innovation & Technology Center (the "Project") located on the 1800 block of Arch Street in Philadelphia, Pennsylvania. The 59 -story building will include 1.3 million square feet of rentable office space and a 222 -room Four Seasons Hotel. Completion of the first phase of the Project is anticipated to be in the third quarter of 2017. Project costs for the development of the Project, exclusive of tenant-funded interior improvements, are anticipated to be approximately $932 million . The Company's investment in the Project is expected to be approximately $185 million with 20% ownership interests in both joint ventures. The two joint ventures have engaged the Company as the developer of the Project pursuant to a Development Agreement by which the Company agrees, in consideration for a development fee, to be responsible for all aspects of the development of the Project and to guarantee the timely lien-free completion of construction of the Project and the payment, subject to certain exceptions, of any cost overruns incurred in the development of the Project. Liberty Venture I, LP During the three and six months ended June 30, 2015 , Liberty Venture I, LP (a joint venture in which the Company holds a 25% interest) realized proceeds of $8.5 million from the sale of one property totaling 198,000 square feet.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest rate swaps [Text Block]	Derivative Instruments The Company borrows funds at a combination of fixed and variable rates. Borrowings under the Company's revolving credit facility and certain bank mortgage loans bear interest at variable rates. Our long-term debt typically bears interest at fixed rates. Our interest rate risk management objectives are to limit generally the impact of interest rate changes on earnings and cash flows and to lower our overall borrowing costs. To achieve these objectives, from time to time, we enter into interest rate hedge contracts such as collars, swaps, caps and treasury lock agreements in order to mitigate our interest rate risk with respect to various debt instruments. We generally do not hold or issue these derivative contracts for trading or speculative purposes. The interest rate on all of our variable rate debt is generally adjusted at one or three month intervals, subject to settlements under interest rate hedge contracts. Interest rate swaps involve the receipt of variable-rate amounts from a counterparty in exchange for making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive loss (for the Trust) and general partner's equity and limited partners' equity - common units (for the Operating Partnership) and is subsequently reclassified into interest expense in the period that the hedged forecasted transaction affects earnings. The Company determines the fair value of its interest rate swaps by using the standard methodology of netting discounted future fixed cash payments with the discounted expected variable cash receipts. These variable cash receipts of interest rate swaps are based on expectations of future LIBOR interest rates (forward curves) estimated by observing market LIBOR interest rate curves. This is a Level 2 fair value calculation. Also, credit valuation adjustments are factored into the fair value calculations to account for potential nonperformance risk. These credit valuation adjustments were concluded to be not significant inputs for the fair value calculations for the periods presented. The Company holds interest in three interest rate swap contracts (“Swaps”) that eliminate the impact of changes in interest rates on the payments required under variable rate mortgages. The Swaps had aggregate notional amounts of $102.6 million and $103.6 million at June 30, 2015 and December 31, 2014 , respectively, and expire at various dates between 2018 and 2020 . The Company accounts for the effective portion of changes in the fair value of a derivative in accumulated other comprehensive income (loss) and subsequently reclassifies the effective portion to earnings over the term that the hedged transaction affects earnings. The Company accounts for the ineffective portion of changes in the fair value of a derivative directly in earnings. The following table presents the location in the financial statements of the gains or losses recognized related to the Company’s cash flow hedges for the three and six months ended June 30, 2015 and 2014: Three Months Ended Six Months Ended June 30, 2015 June 30, 2014 June 30, 2015 June 30, 2014 (in thousands) Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss) $ 277 $ (1,511 ) $ (1,022 ) $ (2,382 ) Amount of gain (loss) related to the effective portion subsequently reclassified to earnings $ (351 ) $ (366 ) $ (703 ) $ (726 ) Amount of gain (loss) related to the ineffective portion $ (2 ) $ (37 ) $ (62 ) $ (55 ) The fair value of the Swaps in the amounts of $7.9 million and $8.5 million as of June 30, 2015 and December 31, 2014 , respectively, is included in other liabilities in the accompanying consolidated balance sheets. The Company estimates that $1.2 million will be reclassified from accumulated other comprehensive income as an increase to interest expense over the next 12 months. The Company has agreements with its derivative counterparties that contain a provision whereby if the Company defaults on any of its indebtedness, including defaults where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. If the Company were to breach any of the contractual provisions of the derivative contracts, it would be required to settle its obligations under the agreements at their termination value including accrued interest for approximately $8.0 million as of June 30, 2015 .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental Matters Substantially all of the Company's properties and land were subject to Phase I Environmental Assessments and when appropriate Phase II Environmental Assessments (collectively, the “Environmental Assessments”) obtained in contemplation of their acquisition by the Company or obtained by predecessor owners prior to the sale of the property or land to the Company. The Environmental Assessments did not reveal, nor is the Company aware of, any non-compliance with environmental laws, environmental liability or other environmental claim that the Company believes would likely have a material adverse effect on the Company. Operating Ground Lease Agreements Future minimum rental payments under the terms of all non-cancelable operating ground leases under which the Company is the lessee, as of June 30, 2015 , were as follows (in thousands): Year Amount 2015 $ 393 2016 785 2017 785 2018 785 2019 785 2020 through 2034 8,013 Total $ 11,546 Operating ground lease expense for the three and six months ended June 30, 2015 was $156,000 and $312,000 as compared to $91,000 and $175,000 for the same periods in 2014 , respectively. Legal Matters From time to time, the Company is a party to a variety of legal proceedings, claims and assessments arising in the normal course of business. As of June 30, 2015 there were no legal proceedings, claims or assessments that the Company expects to have a material adverse effect on the Company’s business or financial statements. Other As of June 30, 2015 , the Company had letter of credit obligations of $4.2 million . The Company believes that the likelihood is remote that there will be a draw upon these letter of credit obligations. As of June 30, 2015 , the Company had 21 buildings under development. These buildings are expected to contain, when completed, a total of 3.0 million square feet of leasable space and represent an anticipated aggregate investment of $361.2 million . At June 30, 2015 , development in progress totaled $225.2 million . In addition, as of June 30, 2015 , the Company had invested $7.1 million in deferred leasing costs related to these development buildings. In addition, the Company had signed commitments for build-to-suit developments not yet commenced for an anticipated aggregate investment of $184.6 million . As of June 30, 2015 , the Company was committed to $39.3 million in improvements on certain buildings and land parcels. As of June 30, 2015 , the Company was committed to $50.8 million in future land purchases. As of June 30, 2015 , the Company was obligated to pay for tenant improvements not yet completed for a maximum of $34.8 million . The Company maintains cash and cash equivalents at financial institutions. The combined account balances at each institution typically exceed FDIC insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. The Company believes the risk is not significant.

Supplemental Disclosure to Stat

Supplemental Disclosure to Statements of Cash Flows	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure to Statements of Cash Flows	Supplemental Disclosure to Statements of Cash Flows The following are supplemental disclosures to the statements of cash flows for the six months ended June 30, 2015 and 2014 (amounts in thousands): 2015 2014 Write-off of fully depreciated/amortized property and deferred costs $ 28,877 $ 20,672 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 76,533 $ 132,707 Unrealized loss on cash flow hedge $ (319 ) $ (1,656 ) Changes in accrued development capital expenditures $ (10,974 ) $ 4,280 Increase in investments in and advances to unconsolidated joint ventures $ — $ (11,948 ) Amounts paid in cash for deferred leasing costs incurred in connection with signed leases with tenants are paid in conjunction with improving (acquiring) property, plant and equipment. Such costs are not contained within net real estate. However, they are integral to the completion of a tenant lease and ultimately are related to the improvement and thus the value of the Company’s property, plant and equipment. They are therefore included in investing activities in the Company’s consolidated statements of cash flows.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2015
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events Subsequent to June 30, 2015, Liberty Washington, LP (a joint venture in which the Company holds a 25% interest) received a letter of default on a $46.4 million non-recourse mortgage loan related to certain properties within the joint venture in the Company's Northern Virginia segment.

Organization and Basis of Pre24

Organization and Basis of Presentation (Policy)	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which supersedes nearly all existing revenue recognition guidance. The standard clarifies the required factors that an entity must consider when recognizing revenue. The standard also requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company is evaluating the impact ASU 2014-09 will have on its financial position and results of operations. In April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The standard requires the costs for issuing debt to appear on a balance sheet as a direct deduction from the debt's value. ASU 2015-03 is effective for the Company beginning January 1, 2016. The standard would be applied retrospectively. The Company does not anticipate that the adoption of ASU 2015-03 will have a material impact on its financial position or results of operations.

Income per Common Share of th25

Income per Common Share of the Trust (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 148,778 $ 0.24 $ 28,961 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 149,454 $ 0.24 $ 28,961 147,774 $ 0.20 Basic income from discontinued operations Discontinued operations net of noncontrolling interest $ — 148,778 $ — $ 288 147,012 $ — Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest $ — 149,454 $ — $ 288 147,774 $ — Basic income per common share Net income available to common shareholders $ 35,513 148,778 $ 0.24 $ 29,249 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income per common share Net income available to common shareholders $ 35,513 149,454 $ 0.24 $ 29,249 147,774 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 66,464 148,574 $ 0.45 $ 54,137 146,749 $ 0.37 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest 66,464 149,247 $ 0.45 54,137 147,444 $ 0.37 Basic income from discontinued operations Discontinued operations net of noncontrolling interest — 148,574 $ — 47,012 146,749 $ 0.32 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest — 149,247 $ — 47,012 147,444 $ 0.32 Basic income per common share Net income available to common shareholders 66,464 148,574 $ 0.45 101,149 146,749 $ 0.69 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income per common share Net income available to common shareholders $ 66,464 149,247 $ 0.45 $ 101,149 147,444 $ 0.69

Income per Common Unit of the26

Income per Common Unit of the Operating Partnership (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share, Basic and Diluted [Line Items]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 148,778 $ 0.24 $ 28,961 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest $ 35,513 149,454 $ 0.24 $ 28,961 147,774 $ 0.20 Basic income from discontinued operations Discontinued operations net of noncontrolling interest $ — 148,778 $ — $ 288 147,012 $ — Dilutive shares for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest $ — 149,454 $ — $ 288 147,774 $ — Basic income per common share Net income available to common shareholders $ 35,513 148,778 $ 0.24 $ 29,249 147,012 $ 0.20 Dilutive shares for long-term compensation plans — 676 — 762 Diluted income per common share Net income available to common shareholders $ 35,513 149,454 $ 0.24 $ 29,249 147,774 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Basic income from continuing operations Income from continuing operations net of noncontrolling interest $ 66,464 148,574 $ 0.45 $ 54,137 146,749 $ 0.37 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations net of noncontrolling interest 66,464 149,247 $ 0.45 54,137 147,444 $ 0.37 Basic income from discontinued operations Discontinued operations net of noncontrolling interest — 148,574 $ — 47,012 146,749 $ 0.32 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations net of noncontrolling interest — 149,247 $ — 47,012 147,444 $ 0.32 Basic income per common share Net income available to common shareholders 66,464 148,574 $ 0.45 101,149 146,749 $ 0.69 Dilutive shares for long-term compensation plans — 673 — 695 Diluted income per common share Net income available to common shareholders $ 66,464 149,247 $ 0.45 $ 101,149 147,444 $ 0.69
Liberty Property Limited Partnership [Member]
Earnings Per Share, Basic and Diluted [Line Items]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted income per common unit of the Operating Partnership (in thousands, except per unit amounts): For the Three Months Ended For the Three Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income from continuing operations - net of noncontrolling interest - consolidated joint ventures $ 36,471 $ 29,775 Less: Preferred unit distributions (118 ) (118 ) Basic income from continuing operations Income from continuing operations available to common unitholders $ 36,353 152,317 $ 0.24 $ 29,657 150,563 $ 0.20 Dilutive units for long-term compensation plans — 676 — 762 Diluted income from continuing operations Income from continuing operations available to common unitholders $ 36,353 152,993 $ 0.24 $ 29,657 151,325 $ 0.20 Basic income from discontinued operations Discontinued operations $ — 152,317 $ — $ 295 150,563 $ — Dilutive units for long-term compensation plans — 676 — 762 Diluted income from discontinued operations Discontinued operations $ — 152,993 $ — $ 295 151,325 $ — Basic income per common unit Income available to common unitholders $ 36,353 152,317 $ 0.24 $ 29,952 150,563 $ 0.20 Dilutive units for long-term compensation plans — 676 — 762 Diluted income per common unit Income available to common unitholders $ 36,353 152,993 $ 0.24 $ 29,952 151,325 $ 0.20 For the Six Months Ended For the Six Months Ended June 30, 2015 June 30, 2014 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income from continuing operations net of noncontrolling interest - consolidated joint ventures $ 68,275 $ 55,680 Less: Preferred unit distributions (236 ) (236 ) Basic income from continuing operations Income from continuing operations available to common unitholders 68,039 152,114 $ 0.45 55,444 150,304 $ 0.37 Dilutive units for long-term compensation plans — 673 — 695 Diluted income from continuing operations Income from continuing operations available to common unitholders 68,039 152,787 $ 0.45 55,444 150,999 $ 0.37 Basic income from discontinued operations Discontinued operations — 152,114 $ — 48,143 150,304 $ 0.32 Dilutive units for long-term compensation plans — 673 — 695 Diluted income from discontinued operations Discontinued operations — 152,787 $ — 48,143 150,999 $ 0.32 Basic income per common unit Income available to common unitholders 68,039 152,114 $ 0.45 103,587 150,304 $ 0.69 Dilutive units for long-term compensation plans — 673 — 695 Diluted income per common unit Income available to common unitholders $ 68,039 152,787 $ 0.45 $ 103,587 150,999 $ 0.69

Accumulated Other Comprehensi27

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table sets forth the components of Accumulated Other Comprehensive Income (Loss) (in thousands): Six Months Ended June 30, 2015 2014 Foreign Currency Translation: Beginning balance $ (5,823 ) $ 8,592 Translation adjustment 1,741 7,811 Ending balance (4,082 ) 16,403 Derivative Instruments: Beginning balance (377 ) 1,584 Unrealized loss (1,022 ) (2,382 ) Reclassification adjustment (1) 703 726 Ending balance (696 ) (72 ) Total accumulated other comprehensive (loss) income (4,778 ) 16,331 Less: portion included in noncontrolling interest – operating partnership (85 ) (579 ) Total accumulated other comprehensive (loss) income included in shareholders' equity/owners' equity $ (4,863 ) $ 15,752 (1) Amounts reclassified out of Accumulated Other Comprehensive (Loss) Income/General & Limited Partner's Equity into contractual interest expense.

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting, Measurement Disclosures [Abstract]
Schedule of Segment Reporting Information, by Segment, Revenue and Net Operating Income [Table Text Block]	The operating information by reportable segment is as follows (in thousands): For the Three Months For the Six Months Ended June 30, Ended June 30, 2015 2014 2015 2014 Operating revenue Carolinas $ 10,062 $ 8,486 $ 19,906 $ 16,803 Chicago/Milwaukee 8,931 8,152 18,724 16,723 Houston 13,151 12,128 25,474 23,995 Lehigh/Central PA 32,844 28,195 66,398 57,819 Minnesota 12,276 13,541 24,948 27,292 Orlando 5,409 8,061 10,674 16,056 Philadelphia 9,889 8,691 19,871 18,099 Richmond/Hampton Roads 10,150 10,115 20,641 20,184 South Florida 12,378 11,707 24,585 24,016 Southeastern PA 38,473 36,309 77,712 74,746 Tampa 13,637 13,230 27,099 26,404 United Kingdom 3,965 4,218 7,690 8,320 Other 32,439 30,122 66,834 65,158 Segment-level operating revenue 203,604 192,955 410,556 395,615 Reconciliation to total operating revenues Discontinued operations — 29 — (4,719 ) Other (86 ) (24 ) (137 ) (306 ) Total operating revenue $ 203,518 $ 192,960 $ 410,419 $ 390,590 Net operating income Carolinas $ 7,066 $ 5,693 $ 13,684 $ 11,435 Chicago/Milwaukee 6,125 4,973 12,868 10,136 Houston 7,689 7,232 14,910 14,284 Lehigh/Central PA 23,647 19,773 46,618 39,013 Minnesota 5,149 6,770 11,134 13,390 Orlando 3,685 5,354 7,256 10,846 Philadelphia 7,310 6,790 14,332 13,511 Richmond/Hampton Roads 6,295 6,054 12,524 11,973 South Florida 7,149 6,891 13,978 14,418 Southeastern PA 21,426 20,060 42,414 39,660 Tampa 8,625 8,488 17,327 16,929 United Kingdom 2,782 2,722 5,298 5,572 Other 21,516 19,167 44,387 40,898 Segment-level net operating income 128,464 119,967 256,730 242,065 Reconciliation to income from continuing operations Interest expense (1) (35,066 ) (38,470 ) (69,736 ) (78,234 ) Depreciation/amortization expense (1) (2) (41,772 ) (44,561 ) (85,281 ) (89,098 ) Impairment - real estate assets (1,036 ) — (16,775 ) — Gain on property dispositions 1,249 1,897 3,520 1,898 Equity in (loss) earnings of unconsolidated joint ventures (5,254 ) 1,546 1,652 5,705 General and administrative expense (1) (2) (9,128 ) (8,232 ) (19,437 ) (20,633 ) Discontinued operations excluding interest and gain on property dispositions — (156 ) — (2,446 ) Income taxes (2) (1,051 ) (663 ) (1,757 ) (1,146 ) Other 120 (1,516 ) (528 ) (2,041 ) Income from continuing operations $ 36,526 $ 29,812 $ 68,388 $ 56,070 (1) Includes activity on discontinued operations. (2) Excludes costs which are included in determining segment-level net operating income.
Real Estate Properties Sold [Table Text Block]	The Company's sales by reportable segment for the three and six months ended June 30, 2015 are as follows: Three months ended June 30, 2015 Six months ended June 30, 2015 Properties Sold Square Feet (000s) Proceeds (000s) Properties Sold Square Feet (000s) Proceeds (000s) Minnesota 1 87 $ 5,800 1 87 $ 5,800 Richmond/Hampton Roads 22 1,319 110,300 (1) 22 1,319 110,300 (1) Southeastern PA — — — 1 83 8,720 Other — — — 6 539 33,512 Total 23 1,406 $ 116,100 30 2,028 $ 158,332 (1) Includes proceeds from the sale of 3.1 acres of land.
Assets by Segment and Reconciliation to Consolidated[Table Text Block]	The Company's total assets by reportable segment as of June 30, 2015 and December 31, 2014 is as follows (in thousands): June 30, 2015 December 31, 2014 Total assets Carolinas $ 329,705 $ 325,690 Chicago/Milwaukee 425,320 422,531 Houston 424,481 418,154 Lehigh/Central PA 1,046,162 1,023,641 Minnesota 330,856 333,506 Orlando 162,167 160,899 Philadelphia 390,707 366,577 Richmond/Hampton Roads 124,246 250,205 South Florida 410,717 400,034 Southeastern PA 675,774 698,163 Tampa 332,784 335,652 United Kingdom 228,624 231,276 Other 1,566,591 1,553,250 Segment-level total assets 6,448,134 6,519,578 Corporate Other 108,596 105,958 Total assets $ 6,556,730 $ 6,625,536

Accounting for the Impairment29

Accounting for the Impairment or Disposal of Long-Lived Assets (Tables)	6 Months Ended
	Jun. 30, 2015
Disposal Group, Including Discontinued Operation, Long Lived Assets [Abstract]
Discontinued Operations, Income Statement [Table Text Block]	A summary of the results of operations for the properties classified as discontinued operations through the respective disposition dates is as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Revenues $ — $ (29 ) $ — $ 4,719 Operating expenses — 183 — (2,312 ) Interest and other income — 2 — 39 Interest expense — — — (557 ) Depreciation and amortization — — — — Income before gain on property dispositions — 156 — 1,889 Gain on property dispositions — 139 — 46,254 Net income $ — $ 295 $ — $ 48,143

Noncontrolling Interest - Ope30

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Tables)	6 Months Ended
	Jun. 30, 2015
Temporary Equity [Line Items]
Schedule of Temporary Equity [Table Text Block]	As of June 30, 2015 , the Company had outstanding the following cumulative preferred units of the Operating Partnership: ISSUE AMOUNT UNITS LIQUIDATION PREFERENCE DIVIDEND RATE (in 000’s) Series I-2 $ 7,537 301 $25 6.25 %

Disclosure of Fair Value of F31

Disclosure of Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Instrument, Fair Value Disclosure [Abstract]
Fair Value, by Balance Sheet Grouping [Table Text Block]	The following summarizes the fair value of the Company's mortgage loans and unsecured notes as of December 31, 2014 and June 30, 2015 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2014 $ 487,301 $ 501,231 $ 2,509,094 $ 2,704,069 As of June 30, 2015 $ 481,621 $ 494,561 $ 2,608,089 $ 2,639,474

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table presents the location in the financial statements of the gains or losses recognized related to the Company’s cash flow hedges for the three and six months ended June 30, 2015 and 2014: Three Months Ended Six Months Ended June 30, 2015 June 30, 2014 June 30, 2015 June 30, 2014 (in thousands) Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss) $ 277 $ (1,511 ) $ (1,022 ) $ (2,382 ) Amount of gain (loss) related to the effective portion subsequently reclassified to earnings $ (351 ) $ (366 ) $ (703 ) $ (726 ) Amount of gain (loss) related to the ineffective portion $ (2 ) $ (37 ) $ (62 ) $ (55 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rental Payments	Future minimum rental payments under the terms of all non-cancelable operating ground leases under which the Company is the lessee, as of June 30, 2015 , were as follows (in thousands): Year Amount 2015 $ 393 2016 785 2017 785 2018 785 2019 785 2020 through 2034 8,013 Total $ 11,546

Supplemental Disclosure to St34

Supplemental Disclosure to Statements of Cash Flows (Tables)	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure to Statements of Cash Flows	The following are supplemental disclosures to the statements of cash flows for the six months ended June 30, 2015 and 2014 (amounts in thousands): 2015 2014 Write-off of fully depreciated/amortized property and deferred costs $ 28,877 $ 20,672 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 76,533 $ 132,707 Unrealized loss on cash flow hedge $ (319 ) $ (1,656 ) Changes in accrued development capital expenditures $ (10,974 ) $ 4,280 Increase in investments in and advances to unconsolidated joint ventures $ — $ (11,948 )

Organization and Basis of Pre35

Organization and Basis of Presentation (Narrative) (Details)	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Ownership interest in operating partnership - Limited Partnership	97.70%

Income per Common Share of th36

Income per Common Share of the Trust (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 35,513	$ 28,961	$ 66,464	$ 54,137
Discontinued operations net of noncontrolling interest	0	288	0	47,012
Net income available to common shareholders	$ 35,513	$ 29,249	$ 66,464	$ 101,149
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	148,778	147,012	148,574	146,749
Dilutive shares for long-term compensation plans	676	762	673	695
Weighted Average Number of Shares Outstanding, Diluted	149,454	147,774	149,247	147,444
Common shares [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.24	$ 0.20	$ 0.45	$ 0.37
Income from Discontinued Operations, Per Basic Share	0	0	0	0.32
Income per common share - basic	0.24	0.20	0.45	0.69
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	0.24	0.20	0.45	0.37
Income from Discontinued Operations, Per Diluted Share	0	0	0	0.32
Income per common share - diluted	$ 0.24	$ 0.20	$ 0.45	$ 0.69

Income per Common Share of th37

Income per Common Share of the Trust, Anti-dilutive (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Stock Option [Member]
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	1,528,000	750,000	1,448,000	750,000

Income per Common Share of th38

Income per Common Share of the Trust, Dilutive (Details) - shares	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Stock Option [Member] | Common shares [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	8,000	53,000	44,000

Income per Common Unit of the39

Income per Common Unit of the Operating Partnership, Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 35,513	$ 28,961	$ 66,464	$ 54,137
Discontinued operations	0	295	0	48,143
Net income available to common shareholders	$ 35,513	$ 29,249	$ 66,464	$ 101,149
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	148,778	147,012	148,574	146,749
Dilutive units for long-term compensation plans	676	762	673	695
Weighted Average Number of Shares Outstanding, Diluted	149,454	147,774	149,247	147,444
Liberty Property Limited Partnership [Member]
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 36,471	$ 29,775	$ 68,275	$ 55,680
Less: Preferred unit distributions	(118)	(118)	(236)	(236)
Income from Continuing Operations available to Common Unitholders	36,353	29,657	68,039	55,444
Discontinued operations	0	295	0	48,143
Net income available to common shareholders	$ 36,353	$ 29,952	$ 68,039	$ 103,587
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	152,317	150,563	152,114	150,304
Dilutive units for long-term compensation plans	676	762	673	695
Weighted Average Number of Shares Outstanding, Diluted	152,993	151,325	152,787	150,999
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.24	$ 0.20	$ 0.45	$ 0.37
Income from Discontinued Operations, Per Basic Share	0	0	0	0.32
Income per common share - basic	0.24	0.20	0.45	0.69
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	0.24	0.20	0.45	0.37
Income from Discontinued Operations, Per Diluted Share	0	0	0	0.32
Income per common share - diluted	$ 0.24	$ 0.20	$ 0.45	$ 0.69

Income per Common Unit of the40

Income per Common Unit of the Operating Partnership, Anti-dilutive Options (Details) - Stock Option [Member] - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	1,528,000	750,000	1,448,000	750,000
Liberty Property Limited Partnership [Member]
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	1,528,000	750,000	1,448,000	750,000

Income per Common Unit of the41

Income per Common Unit of the Operations Partnership, Dilutive Options (Details) - shares	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Liberty Property Limited Partnership [Member] | Stock Option [Member] | Common Units [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	8,000	53,000	44,000

Accumulated Other Comprehensi42

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Foreign Currency Translation:
Beginning balance		$ (5,823)	$ 8,592
Translation adjustment		1,741	7,811
Ending balance		(4,082)	16,403
Derivative Instruments:
Beginning balance		(377)	1,584
Unrealized loss		(1,022)	(2,382)
Reclassification adjustment	[1]	703	726
Ending balance		(696)	(72)
Total accumulated other comprehensive (loss) income		(4,778)	16,331
Less: portion included in noncontrolling interest - operating partnership		(85)	(579)
Total accumulated other comprehensive (loss) income included in shareholders' equity/owners' equity		$ (4,863)	$ 15,752	$ (6,252)
[1]	Amounts reclassified out of Accumulated Other Comprehensive (Loss) Income/General & Limited Partner's Equity into contractual interest expense.

Performance of the Reportable S

Performance of the Reportable Segments Based on Property Level Operating Income (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Operating revenue		$ 203,518,000	$ 192,960,000	$ 410,419,000	$ 390,590,000
Net operating income		70,185,000	62,417,000	122,014,000	121,815,000
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense		(35,066,000)	(38,470,000)	(69,736,000)	(77,677,000)
Depreciation and amortization expense				(117,160,000)	(116,547,000)
Impairment - real estate assets		(1,036,000)	0	(16,775,000)	0
Gain on property dispositions		1,249,000	1,897,000	3,520,000	1,898,000
Equity in (loss) earnings of unconsolidated joint ventures		(5,254,000)	1,546,000	1,652,000	5,705,000
General and administrative expense		(17,053,000)	(14,973,000)	(35,855,000)	(33,329,000)
Income taxes		(1,169,000)	(693,000)	(2,014,000)	(1,224,000)
Income from continuing operations		36,526,000	29,812,000	68,388,000	56,070,000
Richmond Hampton Roads [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Impairment - real estate assets				(13,400,000)
Southeastern PA [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Impairment - real estate assets				(2,300,000)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenue		0	0	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenue		203,604,000	192,955,000	410,556,000	395,615,000
Net operating income		128,464,000	119,967,000	256,730,000	242,065,000
Operating Segments [Member] | Carolinas [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		10,062,000	8,486,000	19,906,000	16,803,000
Net operating income		7,066,000	5,693,000	13,684,000	11,435,000
Operating Segments [Member] | Chicago Milwaukee [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		8,931,000	8,152,000	18,724,000	16,723,000
Net operating income		6,125,000	4,973,000	12,868,000	10,136,000
Operating Segments [Member] | Houston [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		13,151,000	12,128,000	25,474,000	23,995,000
Net operating income		7,689,000	7,232,000	14,910,000	14,284,000
Operating Segments [Member] | Lehigh Central PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		32,844,000	28,195,000	66,398,000	57,819,000
Net operating income		23,647,000	19,773,000	46,618,000	39,013,000
Operating Segments [Member] | Minnesota [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		12,276,000	13,541,000	24,948,000	27,292,000
Net operating income		5,149,000	6,770,000	11,134,000	13,390,000
Operating Segments [Member] | Orlando [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		5,409,000	8,061,000	10,674,000	16,056,000
Net operating income		3,685,000	5,354,000	7,256,000	10,846,000
Operating Segments [Member] | Philadelphia [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		9,889,000	8,691,000	19,871,000	18,099,000
Net operating income		7,310,000	6,790,000	14,332,000	13,511,000
Operating Segments [Member] | Richmond Hampton Roads [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		10,150,000	10,115,000	20,641,000	20,184,000
Net operating income		6,295,000	6,054,000	12,524,000	11,973,000
Operating Segments [Member] | South Florida [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		12,378,000	11,707,000	24,585,000	24,016,000
Net operating income		7,149,000	6,891,000	13,978,000	14,418,000
Operating Segments [Member] | Southeastern PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		38,473,000	36,309,000	77,712,000	74,746,000
Net operating income		21,426,000	20,060,000	42,414,000	39,660,000
Operating Segments [Member] | Tampa [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		13,637,000	13,230,000	27,099,000	26,404,000
Net operating income		8,625,000	8,488,000	17,327,000	16,929,000
Operating Segments [Member] | United Kingdom [Member] | UNITED KINGDOM
Segment Reporting Information [Line Items]
Operating revenue		3,965,000	4,218,000	7,690,000	8,320,000
Net operating income		2,782,000	2,722,000	5,298,000	5,572,000
Operating Segments [Member] | Other Segments [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		32,439,000	30,122,000	66,834,000	65,158,000
Net operating income		21,516,000	19,167,000	44,387,000	40,898,000
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Operating revenue		0	29,000	0	(4,719,000)
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenue		(86,000)	(24,000)	(137,000)	(306,000)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense	[1]	(35,066,000)	(38,470,000)	(69,736,000)	(78,234,000)
Depreciation and amortization expense	[1],[2]	(41,772,000)	(44,561,000)	(85,281,000)	(89,098,000)
Impairment - real estate assets		(1,036,000)	0	(16,775,000)	0
Gain on property dispositions		1,249,000	1,897,000	3,520,000	1,898,000
Equity in (loss) earnings of unconsolidated joint ventures		(5,254,000)	1,546,000	1,652,000	5,705,000
General and administrative expense	[1],[2]	(9,128,000)	(8,232,000)	(19,437,000)	(20,633,000)
Discontinued operations excluding interest and gain on property dispositions		0	(156,000)	0	(2,446,000)
Income taxes	[2]	(1,051,000)	(663,000)	(1,757,000)	(1,146,000)
Other		$ 120,000	$ (1,516,000)	$ (528,000)	$ (2,041,000)
[1]	Includes activity on discontinued operations.
[2]	Excludes costs which are included in determining segment-level net operating income.

Segment Information Building Ac

Segment Information Building Acquisitions and Dispositions (Details) - Jun. 30, 2015 $ in Thousands	USD ($)ft²abldg		USD ($)ft²abldg
Land, Buildings and Improvements [Member]
Dispositions [Abstract]
Proceeds from Sale of Property | $	$ 116,100		$ 158,332
Number of Real Estate Properties Sold | bldg	23		30
Sold Real Estate Property, Square Feet	1,406,000		2,028,000
Southern California [Member] | Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Residential Real Estate | $	$ 36,700		$ 36,700
Acquisitions [Abstract]
Number of real estate properties acquired | bldg	1		1
Acquired Real Estate Property, Square Feet	410,000		410,000
Minnesota [Member] | Land, Buildings and Improvements [Member]
Dispositions [Abstract]
Proceeds from Sale of Property | $	$ 5,800		$ 5,800
Number of Real Estate Properties Sold | bldg	1		1
Sold Real Estate Property, Square Feet	87,000		87,000
Richmond Hampton Roads [Member] | Land and Land Improvements [Member]
Dispositions [Abstract]
Sold Land, Acres | a	3.1		3.1
Richmond Hampton Roads [Member] | Land, Buildings and Improvements [Member]
Dispositions [Abstract]
Proceeds from Sale of Property | $	$ 110,300	[1]	$ 110,300	[2]
Number of Real Estate Properties Sold | bldg	22		22
Sold Real Estate Property, Square Feet	1,319,000		1,319,000
Southeastern PA [Member] | Land, Buildings and Improvements [Member]
Dispositions [Abstract]
Proceeds from Sale of Property | $	$ 0		$ 8,720
Number of Real Estate Properties Sold | bldg	0		1
Sold Real Estate Property, Square Feet	0		83,000
Other Segments [Member] | Land, Buildings and Improvements [Member]
Dispositions [Abstract]
Proceeds from Sale of Property | $	$ 0		$ 33,512
Number of Real Estate Properties Sold | bldg	0		6
Sold Real Estate Property, Square Feet	0		539,000
[1]	Includes proceeds from the sale of 3.1 acres of land.
[2]	Includes proceeds from the sale of 3.1 acres of land.

Segment Information Related Par

Segment Information Related Party (Details) - Jun. 30, 2015 $ in Thousands		USD ($)abldg		USD ($)abldg
Land, Buildings and Improvements [Member]
Related Party Transaction [Line Items]
Number of Real Estate Properties Sold		23		30
Proceeds from Sale of Property | $		$ 116,100		$ 158,332
Land, Buildings and Improvements [Member] | Richmond Hampton Roads [Member]
Related Party Transaction [Line Items]
Number of Real Estate Properties Sold		22		22
Proceeds from Sale of Property | $		$ 110,300	[1]	$ 110,300	[2]
Land, Buildings and Improvements [Member] | Richmond Hampton Roads [Member] | Immediate Family Member of Management or Principal Owner [Member] | Richmond Hampton Roads Sale [Member]
Related Party Transaction [Line Items]
Number of Real Estate Properties Sold		22		22
Proceeds from Sale of Property | $	[1]	$ 110,300		$ 110,300
Land and Land Improvements [Member] | Richmond Hampton Roads [Member]
Related Party Transaction [Line Items]
Sold Land, Acres | a		3.1		3.1
Land and Land Improvements [Member] | Richmond Hampton Roads [Member] | Immediate Family Member of Management or Principal Owner [Member] | Richmond Hampton Roads Sale [Member]
Related Party Transaction [Line Items]
Sold Land, Acres | a		3.1		3.1
[1]	Includes proceeds from the sale of 3.1 acres of land.
[2]	Includes proceeds from the sale of 3.1 acres of land.

Segment Information Total Asset

Segment Information Total Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Assets	$ 6,556,730	$ 6,625,536
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	6,448,134	6,519,578
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	108,596	105,958
North America [Member] | Operating Segments [Member] | Carolinas [Member]
Segment Reporting Information [Line Items]
Assets	329,705	325,690
North America [Member] | Operating Segments [Member] | Chicago Milwaukee [Member]
Segment Reporting Information [Line Items]
Assets	425,320	422,531
North America [Member] | Operating Segments [Member] | Houston [Member]
Segment Reporting Information [Line Items]
Assets	424,481	418,154
North America [Member] | Operating Segments [Member] | Lehigh Central PA [Member]
Segment Reporting Information [Line Items]
Assets	1,046,162	1,023,641
North America [Member] | Operating Segments [Member] | Minnesota [Member]
Segment Reporting Information [Line Items]
Assets	330,856	333,506
North America [Member] | Operating Segments [Member] | Orlando [Member]
Segment Reporting Information [Line Items]
Assets	162,167	160,899
North America [Member] | Operating Segments [Member] | Philadelphia [Member]
Segment Reporting Information [Line Items]
Assets	390,707	366,577
North America [Member] | Operating Segments [Member] | Richmond Hampton Roads [Member]
Segment Reporting Information [Line Items]
Assets	124,246	250,205
North America [Member] | Operating Segments [Member] | South Florida [Member]
Segment Reporting Information [Line Items]
Assets	410,717	400,034
North America [Member] | Operating Segments [Member] | Southeastern PA [Member]
Segment Reporting Information [Line Items]
Assets	675,774	698,163
North America [Member] | Operating Segments [Member] | Tampa [Member]
Segment Reporting Information [Line Items]
Assets	332,784	335,652
North America [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	1,566,591	1,553,250
UNITED KINGDOM | Operating Segments [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Assets	$ 228,624	$ 231,276

Accounting for the Impairment47

Accounting for the Impairment or Disposal of Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Gain on property dispositions	$ 0	$ 139	$ 0	$ 46,254
Net income	0	295	0	48,143
Discontinued Operations [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues	0	(29)	0	4,719
Operating expenses	0	183	0	(2,312)
Interest and other income	0	2	0	39
Interest expense	0	0	0	(557)
Depreciation and amortization	0	0	0	0
Income before gain on property dispositions	0	156	0	1,889
Gain on property dispositions	0	139	0	46,254
Net income	$ 0	$ 295	$ 0	$ 48,143

Accounting for the Impairment48

Accounting for the Impairment or Disposal of Long-Lived Assets Asset Impairment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Property, Plant and Equipment [Line Items]
Impairment - real estate assets	$ 1,036	$ 0	$ 16,775	$ 0
Maryland [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets	$ 1,000		1,000
Richmond Hampton Roads [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets			13,400
Southeastern PA [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets			$ 2,300

Noncontrolling Interests of t49

Noncontrolling Interests of the Trust- Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Redeemable Noncontrolling Interest [Line Items]
Common units, units outstanding not held by the trust	3,539,075	3,553,566
Market value of common units based on closing price	$ 114

Limited Partners' Equity of t50

Limited Partners' Equity of the Operating Partnership - Narrative (Details) - Liberty Property Limited Partnership [Member] - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Limited Partners' Capital Account [Line Items]
Limited Partners' Capital Account, Units Outstanding	3,539,075	3,553,566
market value of the outstanding common units	$ 114

Noncontrolling Interest - Ope51

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Cumulative redeemable preferred units of the Operating Partnership outstanding	$ 7,537	$ 7,537
Series I 2 [Member]
Temporary Equity [Line Items]
Units	301,483	301,483
Liquidation Preference	$ 25
Dividend Rate	6.25%

Indebtedness (Details)

Indebtedness (Details) - Mar. 01, 2015 - Senior Notes [Member] - USD ($) $ in Millions	Total
5.125% Senior Notes [Member]
Unsecured Notes [Abstract]
Debt Instrument, Repurchased Face Amount	$ 300
Interest Rate	5.125%
3.75% Senior Notes [Member]
Unsecured Notes [Abstract]
Debt Instrument, Face Amount	$ 400
Interest Rate	3.75%

Disclosure of Fair Value of F53

Disclosure of Fair Value of Financial Instruments (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Estimate of Fair Value Measurement [Member] | Mortgage Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 494,561	$ 501,231
Estimate of Fair Value Measurement [Member] | Unsecured Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	2,639,474	2,704,069
Portion at Other than Fair Value Measurement [Member] | Mortgage Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	481,621	487,301
Portion at Other than Fair Value Measurement [Member] | Unsecured Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 2,608,089	$ 2,509,094

Unconsolidated Joint Ventures (

Unconsolidated Joint Ventures (Details) - Jun. 30, 2015 $ in Thousands	USD ($)ft²roomstorybldginvestment	USD ($)ft²roomstorybldginvestment
Land, Buildings and Improvements [Member]
LIberty Venture I LP [Abstract]
Proceeds from Sale of Property	$ 116,100	$ 158,332
Number of Real Estate Properties Sold | bldg	23	30
Sold Real Estate Property, Square Feet | ft²	1,406,000	2,028,000
Construction in Progress [Member]
Comcast Innovative and Technology Center [Abstract]
Net Rentable Area | ft²	3,000,000	3,000,000
Total anticipated development cost	$ 361,200	$ 361,200
Liberty Washington, LP [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	25.00%	25.00%
Liberty Washington, LP [Member] | Northern Virginia [Member]
Liberty Washington LP [Abstract]
Impairment of Real Estate, Attributable to Parent	$ 7,600	$ 7,600
Comcast Innovation and Technology Center [Member] | Construction in Progress [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%	20.00%
Comcast Innovative and Technology Center [Abstract]
Number of equity method investments | investment	2	2
Number of stories in a high-rise building | story	59	59
Net Rentable Area | ft²	1,300,000	1,300,000
Number of hotel rooms | room	222	222
Total anticipated development cost	$ 932,000	$ 932,000
Anticipated investment in joint ventures	$ 185,000	$ 185,000
Liberty Venture I, LP [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	25.00%	25.00%
Liberty Venture I, LP [Member] | Land, Buildings and Improvements [Member]
LIberty Venture I LP [Abstract]
Proceeds from Sale of Property	$ 8,500	$ 8,500
Number of Real Estate Properties Sold | bldg	1	1
Sold Real Estate Property, Square Feet | ft²	198,000	198,000

Derivative Instruments (Details

Derivative Instruments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Interest Rate Derivatives [Abstract]
Number of interest rate swap contracts	3		3
aggregate notional amount	$ 102,600		$ 102,600		$ 103,600
Termination value of interest rate swap, including accrued interest	8,000		8,000
Interest Rate Cash Flow Hedges [Abstract]
Fair value of interest rate swaps	7,900		7,900		$ 8,500
Amount estimated to be reclassified from accumulated other comprehensive income as an increase to interest expense	1,200		1,200
Interest Rate Swap [Member] | Other Comprehensive Income (Loss) [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss)	277	$ (1,511)	(1,022)	$ (2,382)
Interest Rate Swap [Member] | Interest Expense [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) related to the effective portion subsequently reclassified to earnings	(351)	(366)	(703)	(726)
Amount of gain (loss) related to the ineffective portion	$ (2)	$ (37)	$ (62)	$ (55)

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Rental Payments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
2,015	$ 393,000		$ 393,000
2,016	785,000		785,000
2,017	785,000		785,000
2,018	785,000		785,000
2,019	785,000		785,000
2020 through 2034	8,013,000		8,013,000
Total	11,546,000		11,546,000
Other Expenses [Abstract]
Operating ground lease expense	$ 156,000	$ 91,000	$ 312,000	$ 175,000

Commitments and Contingencies57

Commitments and Contingencies - Loss Contingencies (Details) - Jun. 30, 2015 $ in Millions	USD ($)
Legal Matters [Abstract]
Loss Contingency, Pending Claims, Number	0
Other [Abstract]
Letter of credit obligations	$ 4.2

Commitments and Contingencies58

Commitments and Contingencies - Supply Commitments (Details) $ in Thousands, ft² in Millions	Jun. 30, 2015USD ($)ft²properties	Dec. 31, 2014USD ($)
Supply Commitment [Line Items]
Development in Process	$ 225,154	$ 277,411
Construction in Progress [Member]
Supply Commitment [Line Items]
Net Rentable Area | ft²	3
Number of Real Estate Properties | properties	21
Total anticipated development cost	$ 361,200
Deferred Costs, Leasing, Gross	7,100
Development Not Yet Commenced [Member]
Supply Commitment [Line Items]
Total anticipated development cost	184,600
Buildings and land parcels [Member]
Supply Commitment [Line Items]
Remaining amount committed or obligated to pay for the benefit of current or future tenants	39,300
Tenant Improvements [Member]
Supply Commitment [Line Items]
Tenant improvements not yet completed	$ 34,800

Commitments and Contingencies59

Commitments and Contingencies - Purchase Commitments (Details) $ in Millions	Jun. 30, 2015USD ($)
Land Purchases [Member]
Long-term Purchase Commitment [Line Items]
Remaining amount commitment to future land purchases	$ 50.8

Supplemental Disclosure to St60

Supplemental Disclosure to Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Supplemental Cash Flow Information [Abstract]
Write off of fully depreciated/amortized property and deferred costs	$ 28,877	$ 20,672
Write off of depreciated property and deferred costs due to sale	76,533	132,707
Unrealized loss on cash flow hedge	(319)	(1,656)
Changes in accrued development capital expenditures	(10,974)	4,280
Non cash change in investment in unconsolidated joint ventures	$ 0	$ (11,948)

Subsequent Events (Details)

Subsequent Events (Details) - Liberty Washington, LP [Member] - USD ($) $ in Millions	Jul. 01, 2015	Jun. 30, 2015
Subsequent Event [Line Items]
Equity Method Investment, Ownership Percentage		25.00%
Subsequent Event [Member]
Subsequent Event [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
Northern Virginia [Member] | Mortgages [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Debt Instrument, Debt Default, Amount	$ 46.4