Liberty Property Trust (LPT) 10-Q 5 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2017	May 02, 2017
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	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		147,212,480
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	Mar. 31, 2017	Dec. 31, 2016
Real Estate [Abstract]
Land and land improvements	$ 1,101,475	$ 1,094,470
Building and improvements	4,531,773	4,501,921
Less accumulated depreciation	(967,251)	(940,115)
Operating real estate	4,665,997	4,656,276
Development in progress	321,331	267,450
Land held for development	345,632	336,569
Net real estate	5,332,960	5,260,295
Cash and cash equivalents	36,535	43,642
Restricted cash	10,680	12,383
Accounts receivable	14,998	13,994
Deferred rent receivable	114,811	109,245
Deferred financing and leasing costs, net of accumulated amortization (March 31, 2017, $156,509; December 31, 2016, $152,309)	155,105	153,393
Investments in and advances to unconsolidated joint ventures	254,864	245,078
Assets held for sale	5,039	4,548
Prepaid expenses and other assets	158,909	150,235
Total assets	6,083,901	5,992,813
LIABILITIES
Mortgage loans	274,260	276,650
Unsecured notes	2,280,970	2,280,286
Credit facility	115,000	0
Accounts payable	56,357	65,914
Accrued interest	34,850	21,878
Dividend and distributions payable	60,293	71,501
Other liabilities	199,718	206,124
Total liabilities	3,021,448	2,922,353
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of March 31, 2017 and December 31, 2016	7,537	7,537
EQUITY
Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 147,203,022 and 146,993,018 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	147	147
Additional paid-in capital	3,660,740	3,655,910
Accumulated other comprehensive loss	(52,622)	(56,031)
Distributions in excess of net income	(612,424)	(596,635)
Total Liberty Property Trust shareholders' equity	2,995,841	3,003,391
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	54,174	54,631
Noncontrolling interest - consolidated joint ventures	4,901	4,901
Total owners' equity	3,054,916	3,062,923
Total liabilities, noncontrolling interest - operating partnership and equity	6,083,901	5,992,813
Liberty Property Limited Partnership [Member]
Real Estate [Abstract]
Land and land improvements	1,101,475	1,094,470
Building and improvements	4,531,773	4,501,921
Less accumulated depreciation	(967,251)	(940,115)
Operating real estate	4,665,997	4,656,276
Development in progress	321,331	267,450
Land held for development	345,632	336,569
Net real estate	5,332,960	5,260,295
Cash and cash equivalents	36,535	43,642
Restricted cash	10,680	12,383
Accounts receivable	14,998	13,994
Deferred rent receivable	114,811	109,245
Deferred financing and leasing costs, net of accumulated amortization (March 31, 2017, $156,509; December 31, 2016, $152,309)	155,105	153,393
Investments in and advances to unconsolidated joint ventures	254,864	245,078
Assets held for sale	5,039	4,548
Prepaid expenses and other assets	158,909	150,235
Total assets	6,083,901	5,992,813
LIABILITIES
Mortgage loans	274,260	276,650
Unsecured notes	2,280,970	2,280,286
Credit facility	115,000	0
Accounts payable	56,357	65,914
Accrued interest	34,850	21,878
Dividend and distributions payable	60,293	71,501
Other liabilities	199,718	206,124
Total liabilities	3,021,448	2,922,353
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of March 31, 2017 and December 31, 2016	7,537	7,537
EQUITY
General partner’s equity - 147,203,022 and 146,993,018 common units outstanding as of March 31, 2017 and December 31, 2016, respectively	2,995,841	3,003,391
Limited partners' equity	54,174	54,631
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	4,901	4,901
Total owners' equity	3,054,916	3,062,923
Total liabilities, noncontrolling interest - operating partnership and equity	$ 6,083,901	$ 5,992,813

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Deferred financing and leasing costs, accumulated amortization	$ 156,509,000	$ 152,308,000
Limited Partners' common units outstanding	3,528,281	3,530,031
Common shares of beneficial interest, par value per share	$ 0.001	$ 0.001
Common shares of beneficial interest, shares authorized	283,987,000	283,987,000
Common shares of beneficial interest, shares issued	147,203,022	146,993,018
Common shares of beneficial interest, shares outstanding	147,203,022	146,993,018
Liberty Property Limited Partnership [Member]
Deferred financing and leasing costs, accumulated amortization	$ 156,509,000	$ 152,308,000
Limited Partners' common units outstanding	3,528,281	3,530,031
Common shares of beneficial interest, shares outstanding	147,203,022	146,993,018
Series I 2 [Member]
Noncontrolling interest - operating partnership, preferred units outstanding	301,483	301,483
Series I 2 [Member] | Liberty Property Limited Partnership [Member]
Noncontrolling interest - operating partnership, preferred units outstanding	301,483	301,483

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING REVENUE
Rental	$ 123,381	$ 139,054
Operating expense reimbursement	40,500	51,086
Development service fee income	11,485	0
Total operating revenue	175,366	190,140
OPERATING EXPENSE
Rental property	19,884	28,509
Real estate taxes	23,281	25,320
General and administrative	16,942	20,990
Depreciation and amortization	45,460	54,078
Development service fee expense	11,004	0
Total operating expenses	116,571	128,897
Operating income	58,795	61,243
OTHER INCOME (EXPENSE)
Interest and other income	1,876	4,598
Interest expense	(22,343)	(31,412)
Total other income (expense)	(20,467)	(26,814)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	38,328	34,429
Gain on property dispositions	807	20,521
Income taxes	(622)	(801)
Equity in earnings of unconsolidated joint ventures	5,731	4,914
Income from continuing operations	44,244	59,063
Net income	44,244	59,063
Noncontrolling interest – operating partnership	(1,149)	(1,509)
Noncontrolling interest - consolidated joint ventures	(63)	0
Net income available to common shareholders	43,032	57,554
Comprehensive income attributable to common shareholders
Net income	44,244	59,063
Other comprehensive gain (loss) - foreign currency translation	3,177	(5,087)
Other comprehensive gain (loss) - derivative instruments	313	(1,360)
Other comprehensive income (loss)	3,490	(6,447)
Total comprehensive income	47,734	52,616
Less: comprehensive income attributable to noncontrolling interest	(1,293)	(1,357)
Comprehensive income attributable to common shareholders	$ 46,441	$ 51,259
Weighted average number of common shares outstanding
Basic	146,471	146,071
Diluted	147,221	146,531
Amounts attributable to common shareholders
Net income available to common shareholders	$ 43,032	$ 57,554
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	123,381	139,054
Operating expense reimbursement	40,500	51,086
Development service fee income	11,485	0
Total operating revenue	175,366	190,140
OPERATING EXPENSE
Rental property	19,884	28,509
Real estate taxes	23,281	25,320
General and administrative	16,942	20,990
Depreciation and amortization	45,460	54,078
Development service fee expense	11,004	0
Total operating expenses	116,571	128,897
Operating income	58,795	61,243
OTHER INCOME (EXPENSE)
Interest and other income	1,876	4,598
Interest expense	(22,343)	(31,412)
Total other income (expense)	(20,467)	(26,814)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures	38,328	34,429
Gain on property dispositions	807	20,521
Income taxes	(622)	(801)
Equity in earnings of unconsolidated joint ventures	5,731	4,914
Net income	44,244	59,063
Noncontrolling interest - consolidated joint ventures	(63)	0
Preferred unit distributions	(118)	(118)
Net income available to common shareholders	44,063	58,945
Comprehensive income attributable to common shareholders
Net income	44,244	59,063
Other comprehensive gain (loss) - foreign currency translation	3,177	(5,087)
Other comprehensive gain (loss) - derivative instruments	313	(1,360)
Other comprehensive income (loss)	3,490	(6,447)
Total comprehensive income	$ 47,734	$ 52,616
Weighted average number of common shares outstanding
Basic	150,000	149,610
Diluted	150,750	150,070
Net income allocated to general partners	$ 43,032	$ 57,554
Net income allocated to limited partners	1,149	1,509
Amounts attributable to common shareholders
Income from continuing operations	44,181	59,063
Net income available to common shareholders	$ 44,063	$ 58,945
Common shares [Member]
Basic:
Income per common share - basic	$ 0.29	$ 0.39
Diluted:
Income per common share - diluted	0.29	0.39
Distributions per common share or unit	0.40	0.475
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income per common share - basic	0.29	0.39
Diluted:
Income per common share - diluted	0.29	0.39
Distributions per common share or unit	$ 0.40	$ 0.475

Consolidated Statement of Equit

Consolidated Statement of Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Accumulated Distributions in Excess of Net Income [Member]	Parent [Member]	Noncontrolling interest operating partnership Common [Member]	Noncontrolling interest-consolidated joint ventures [Member]	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member]General Partner [Member]	Liberty Property Limited Partnership [Member]Limited Partner [Member]	Liberty Property Limited Partnership [Member]Noncontrolling interest-consolidated joint ventures [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income - foreign currency translation	$ (5,087,000)								$ (5,087,000)
Other comprehensive income - derivative instruments	(1,360,000)								(1,360,000)
Beginning Balance at Dec. 31, 2016	3,062,923,000	$ 147,000	$ 3,655,910,000	$ (56,031,000)	$ (596,635,000)	$ 3,003,391,000	$ 54,631,000	$ 4,901,000	3,062,923,000	$ 3,003,391,000	$ 54,631,000	$ 4,901,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from the issuance of common shares	852,000	0	852,000	0	0	852,000	0
Net income	44,126,000	0	0	0	43,032,000	43,032,000	1,031,000	63,000	44,126,000	43,032,000	1,031,000	63,000
Contributions from partners									4,803,000	4,803,000
Distributions	(60,426,000)	0	0	0	(58,821,000)	(58,821,000)	(1,542,000)	(63,000)
Distributions to partners									(60,426,000)	(58,821,000)	(1,542,000)	(63,000)
Share-based compensation	3,951,000	0	3,951,000	0	0	3,951,000
Other comprehensive income - foreign currency translation	3,177,000	0	0	3,103,000	0	3,103,000	74,000		3,177,000	3,103,000	74,000
Other comprehensive income - derivative instruments	313,000	0	0	306,000	0	306,000	7,000		313,000	306,000	7,000
Redemption of noncontrolling interests - common units	0	0	27,000	0	0	27,000	(27,000)		0	27,000	(27,000)
Ending Balance at Mar. 31, 2017	3,054,916,000	$ 147,000	$ 3,660,740,000	$ (52,622,000)	$ (612,424,000)	$ 2,995,841,000	$ 54,174,000	$ 4,901,000	3,054,916,000	$ 2,995,841,000	$ 54,174,000	$ 4,901,000
Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance at Dec. 31, 2016	7,537,000								7,537,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (Mezzanine)	118,000								118,000
Distributions (Mezzanine)	(118,000)								(118,000)
Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance at Mar. 31, 2017	$ 7,537,000								$ 7,537,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES
Net income	$ 44,244	$ 59,063
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,992	54,837
Amortization of deferred financing costs	937	1,002
Equity in earnings of unconsolidated joint ventures	(5,731)	(4,914)
Distributions from unconsolidated joint ventures	0	314
Gain on property dispositions	(807)	(20,521)
Share-based compensation/Non-cash compensation	7,971	14,566
Other	(844)	(1,652)
Changes in operating assets and liabilities:
Restricted cash	1,902	2,216
Accounts receivable	36	(4,030)
Deferred rent receivable	(5,566)	(5,225)
Prepaid expenses and other assets	6,856	(2,926)
Accounts payable	(7,136)	3,762
Accrued interest	12,972	16,976
Other liabilities	(14,444)	(12,627)
Net cash provided by operating activities	86,382	100,841
INVESTING ACTIVITIES
Investment in properties - acquisitions	0	(8,000)
Investment in properties - other	(12,422)	(13,314)
Investments in and advances to unconsolidated joint ventures	(13,278)	(14,635)
Distributions from unconsolidated joint ventures	9,427	26,684
Net proceeds from disposition of properties/land	1,874	127,727
Investment in development in progress	(64,661)	(76,522)
Investment in land held for development	(53,660)	(15,392)
Payment of deferred leasing costs	(7,544)	(8,200)
Investing - Other	9,016	8,095
Net cash (used in) provided by investing activities	(131,248)	26,443
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	852	504
Share repurchase including shares related to tax withholdings	(4,624)	(44,926)
Repayments of mortgage loans	(1,930)	(3,101)
Proceeds from credit facility	159,000	187,000
Repayments on credit facility	(44,000)	(186,000)
Distribution paid on common shares	(69,823)	(70,104)
Distribution paid on units	(1,987)	(1,794)
Net cash provided by (used in) financing activities	37,488	(118,421)
Net (decrease) increase in cash and cash equivalents	(7,378)	8,863
Increase (decrease) in cash and cash equivalents related to foreign currency translation	271	(553)
Cash and cash equivalents at beginning of period	43,642	35,353
Cash and cash equivalents at end of period	36,535	43,663
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	44,244	59,063
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,992	54,837
Amortization of deferred financing costs	937	1,002
Equity in earnings of unconsolidated joint ventures	(5,731)	(4,914)
Distributions from unconsolidated joint ventures	0	314
Gain on property dispositions	(807)	(20,521)
Share-based compensation/Non-cash compensation	7,971	14,566
Other	(844)	(1,652)
Changes in operating assets and liabilities:
Restricted cash	1,902	2,216
Accounts receivable	36	(4,030)
Deferred rent receivable	(5,566)	(5,225)
Prepaid expenses and other assets	6,856	(2,926)
Accounts payable	(7,136)	3,762
Accrued interest	12,972	16,976
Other liabilities	(14,444)	(12,627)
Net cash provided by operating activities	86,382	100,841
INVESTING ACTIVITIES
Investment in properties - acquisitions	0	(8,000)
Investment in properties - other	(12,422)	(13,314)
Investments in and advances to unconsolidated joint ventures	(13,278)	(14,635)
Distributions from unconsolidated joint ventures	9,427	26,684
Net proceeds from disposition of properties/land	1,874	127,727
Investment in development in progress	(64,661)	(76,522)
Investment in land held for development	(53,660)	(15,392)
Payment of deferred leasing costs	(7,544)	(8,200)
Investing - Other	9,016	8,095
Net cash (used in) provided by investing activities	(131,248)	26,443
FINANCING ACTIVITIES
Repayments of mortgage loans	(1,930)	(3,101)
Proceeds from credit facility	159,000	187,000
Repayments on credit facility	(44,000)	(186,000)
Capital contributions	852	504
Distributions to partners/noncontrolling interests	(76,434)	(116,824)
Net cash provided by (used in) financing activities	37,488	(118,421)
Net (decrease) increase in cash and cash equivalents	(7,378)	8,863
Increase (decrease) in cash and cash equivalents related to foreign currency translation	271	(553)
Cash and cash equivalents at beginning of period	43,642	35,353
Cash and cash equivalents at end of period	$ 36,535	$ 43,663

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 . 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. The Operating Partnership is a variable interest entity ("VIE") of the Trust as the limited partners do not have substantive kick-out or participating rights. The Trust is the primary beneficiary of the Operating Partnership as it has the power to direct the activities of the Operating Partnership and the rights to absorb 97.7% of the net income of the Operating Partnership. The Trust has no significant assets or liabilities other than its investment in the Operating Partnership. As the Operating Partnership is already consolidated in the balance sheets of the Trust, the identification of this entity as a VIE has no impact on the consolidated financial statements of the Trust. In addition, the Company holds a 20% interest in Liberty/Comcast 1701 JFK Boulevard, LP which was determined to be a VIE. The Company determined that it is not the primary beneficiary as the Company and its third party partner share control of the joint venture. The Company's maximum exposure to loss is equal to its equity investment in the joint venture which was $18.2 million and $18.7 million as of March 31, 2017 and December 31, 2016, respectively. 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, 2016 . 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. In the fourth quarter of 2016, the Company entered into an agreement relating to the development, for a fee, of an office building at its Camden Waterfront project in Camden, NJ. Project revenues and related costs and expenses are presented on a gross basis as "Development service fee income" and "Development service fee expense" in the Consolidated Statements of Comprehensive Income. Additionally, at the same time, the Company began classifying development fees and expenses relating to its development fee arrangements for certain unconsolidated joint venture projects in a manner consistent with the Camden project described above. Previously, development service fee income relating to its unconsolidated joint ventures had been classified as other income and development service fee expense had been classified as general and administrative expense in amounts as follows: Three months ended March 31, 2016 Other income $ 1,372 General and administrative $ 1,098 In the first quarter of 2017, the Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”), which requires the Company to reclassify shares withheld for tax withholding purposes on share-based compensation awards from operating activities to financing activities. As a result of the adoption, a $4.0 million cash outflow has been reclassified in the March 31, 2016 consolidated statement of cash flows from operating activities to financing activities. 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 (except revenue in the scope of other accounting standards, including standards related to leasing). The standard clarifies the required factors that an entity must consider when recognizing revenue and requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. The standard also provides guidance regarding the measurement of gains and losses relative to the sale of certain nonfinancial assets, including real estate. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company has performed an initial assessment of ASU 2014-09 and plans to adopt the standard using the modified retrospective approach. Upon adoption of ASU 2016-02 (see below), the majority of our revenue will be subject to the allocation provisions outlined within the revenue standard. The Company is currently evaluating the specific implementation requirements for allocating the consideration within our contracts in accordance with ASU 2014-09 as well as other transactions subject to ASU 2014-09. The Company does not expect the new standard to have a material impact on the measurement and recognition of gains and losses on the sale of properties. In February 2016, the FASB issued ASU 2016-02, Leases ("ASU 2016-02"). ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 is effective for the Company beginning January 1, 2019. Early adoption of ASU 2016-02 is permitted. The standard requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. For leases in which the Company is the lessor, the standard requires that the lease and non-lease components of the lease agreement should be separated. Revenue related to the lease component of the contract will be recognized on a straight-line basis, while revenue related to the non-lease component will be recognized under the provisions of ASU 2014-09 (see above). For lease agreements longer than one year in which the Company is the lessee, the Company will measure the present value of the future lease payments and recognize a right-of-use asset and corresponding lease liability on its balance sheet. In addition, the new standard states that only direct leasing costs may be capitalized. The Company is evaluating the impact ASU 2016-02 will have on its financial position and results of operations. In March 2016, the FASB issued ASU 2016-05, Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships ("ASU 2016-05"). ASU 2016-05 states that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under FASB Topic 815 does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. ASU 2016-05 is effective for the Company beginning January 1, 2017. The Company adopted the standard on a prospective basis. The adoption of ASU 2016-05 did not have a material impact on the Company's financial position or results of operations. In March 2016, the FASB issued ASU 2016-09. ASU 2016-09 is designed to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Certain amendments in the standard are applied retrospectively and certain amendments are applied prospectively. The adoption of ASU 2016-09 did not have a material impact on the Company's financial position or results of operations. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 is designed to clarify how entities should classify cash receipts and cash payments in the statement of cash flows. ASU 2016-15 is effective for the Company beginning January 1, 2018. Early adoption of ASU 2016-15 is permitted. The standard requires retrospective application unless it is impracticable to do so. The Company is evaluating the impact ASU 2016-15 will have on its statement of cash flows. In February 2017, the FASB issued ASU 2017-05 Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets ("ASU 2017-05"). ASU 2017-05 is designed to provide guidance on how to recognize gain and losses on sales, including partial sale, of nonfinancial assets to noncustomers. ASU 2017-05 is effective for the Company beginning January 1, 2018. Early adoption is permitted but the standard is required to be adopted concurrently with ASU 2014-09. The Company is evaluating the impact ASU 2017-05 will have on the Company's financial position and results of operations.

Income per Common Share of the

Income per Common Share of the Trust	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 43,032 146,471 $ 0.29 $ 57,554 146,071 $ 0.39 Dilutive shares for long-term compensation plans — 750 — 460 Net income available to common shareholders - diluted $ 43,032 147,221 $ 0.29 $ 57,554 146,531 $ 0.39 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 months ended March 31, 2017 was 188,000 as compared to 2.4 million for the same period in 2016 . During the three months ended March 31, 2017 , 11,000 common shares were issued upon the exercise of options. During the year ended December 31, 2016 , 369,000 common shares were issued upon the exercise of options. Share Repurchase In August 2015, the Company’s Board of Trustees authorized a share repurchase plan under which the Company may purchase up to $250 million of the Company’s outstanding common shares. Purchases made pursuant to the program may be made in either the open market or in privately negotiated transactions from time to time as permitted by securities laws and other legal requirements. There were no purchases under the plan during the three months ended March 31, 2017 .

Income per Common Unit of the O

Income per Common Unit of the Operating Partnership	3 Months Ended
	Mar. 31, 2017
Earnings Per Unit, 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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 43,032 146,471 $ 0.29 $ 57,554 146,071 $ 0.39 Dilutive shares for long-term compensation plans — 750 — 460 Net income available to common shareholders - diluted $ 43,032 147,221 $ 0.29 $ 57,554 146,531 $ 0.39 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 months ended March 31, 2017 was 188,000 as compared to 2.4 million for the same period in 2016 . During the three months ended March 31, 2017 , 11,000 common shares were issued upon the exercise of options. During the year ended December 31, 2016 , 369,000 common shares were issued upon the exercise of options. Share Repurchase In August 2015, the Company’s Board of Trustees authorized a share repurchase plan under which the Company may purchase up to $250 million of the Company’s outstanding common shares. Purchases made pursuant to the program may be made in either the open market or in privately negotiated transactions from time to time as permitted by securities laws and other legal requirements. There were no purchases under the plan during the three months ended March 31, 2017 .
Liberty Property Limited Partnership [Member]
Earnings Per Unit, 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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 44,181 $ 59,063 Less: Preferred unit distributions (118 ) (118 ) Income available to common unitholders - basic $ 44,063 150,000 $ 0.29 $ 58,945 149,610 $ 0.39 Dilutive units for long-term compensation plans — 750 — 460 Income available to common unitholders - diluted $ 44,063 150,750 $ 0.29 $ 58,945 150,070 $ 0.39 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 months ended March 31, 2017 was 188,000 as compared to 2.4 million for the same period in 2016 . During the three months ended March 31, 2017 , 11,000 common units were issued upon exercise of options. During the year ended December 31, 2016 , 369,000 common units were issued upon the exercise of options. Share Repurchase In August 2015, the Company’s Board of Trustees authorized a share repurchase plan under which the Company may purchase up to $250 million of the Company’s outstanding common units. Purchases made pursuant to the program may be made in either the open market or in privately negotiated transactions from time to time as permitted by securities laws and other legal requirements. There were no purchases under the plan during the three months ended March 31, 2017 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Loss The following table sets forth the components of Accumulated Other Comprehensive Loss (in thousands): As of and for the three months ended March 31, 2017 2016 Foreign Currency Translation: Beginning balance $ (56,767 ) $ (17,256 ) Translation adjustment 3,177 (5,087 ) Ending balance (53,590 ) (22,343 ) Derivative Instruments: Beginning balance (455 ) (865 ) Unrealized gain (loss) 127 (1,643 ) Reclassification adjustment (1) 186 283 Ending balance (142 ) (2,225 ) Total accumulated other comprehensive loss (53,732 ) (24,568 ) Less: portion included in noncontrolling interest – operating partnership 1,110 380 Total accumulated other comprehensive loss included in shareholders' equity/owners' equity $ (52,622 ) $ (24,188 ) (1) Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Real Estate

Real Estate	3 Months Ended
	Mar. 31, 2017
Real Estate [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Real Estate During the three months ended March 31, 2017, the Company sold one property in its Southeastern PA reportable segment consisting of 33,000 square feet for gross proceeds of $2.1 million . As of March 31, 2017, the Company classified 16.4 acres of land held for development with a total carrying value of $5.0 million as assets held for sale. This land is located in the Florida reportable segment.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
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. During the three months ended March 31, 2017, the Company realigned its reportable segments as follows: • Carolinas/Richmond; • Chicago/Minneapolis; • Florida; • Houston; • Lehigh/Central PA; • Philadelphia; • Southeastern PA; and • United Kingdom. Certain other segments are aggregated into an "Other" category which includes the reportable segments: Arizona; Atlanta; Cincinnati/Columbus/Indianapolis; Dallas; DC Metro; New Jersey; and Southern California. Comparative prior periods have been restated to reflect current segment disclosures. The Company evaluates the performance of its reportable segments based on segment net operating income (“SNOI”). SNOI is defined as net operating income (rental revenue and operating expense reimbursements less property and real estate tax expenses) less 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): Three Months Ended March 31, 2017 2016 Operating revenue Carolinas/Richmond $ 18,056 $ 15,760 Chicago/Minneapolis 15,875 21,539 Florida 14,248 29,318 Houston 14,774 14,766 Lehigh/Central PA 41,535 34,243 Philadelphia 11,436 10,355 Southeastern PA 14,615 25,883 United Kingdom 3,168 3,552 Other 30,372 34,998 Segment-level operating revenue 164,079 190,414 Reconciliation to total operating revenues Development service fee income 11,485 — Other (198 ) (274 ) Total operating revenue $ 175,366 $ 190,140 SNOI Carolinas/Richmond $ 12,982 $ 10,840 Chicago/Minneapolis 9,349 11,371 Florida 9,511 18,047 Houston 6,801 8,833 Lehigh/Central PA 29,578 24,202 Philadelphia 8,759 7,097 Southeastern PA 8,113 13,751 United Kingdom 1,858 2,405 Other 20,256 22,825 SNOI 107,207 119,371 Reconciliation to net income Interest expense (22,343 ) (31,412 ) Depreciation/amortization expense (1) (33,193 ) (39,798 ) Gain on property dispositions 807 20,521 Equity in earnings of unconsolidated joint ventures 5,731 4,914 General and administrative expense (1) (12,254 ) (14,539 ) Income taxes (1) (280 ) (570 ) Other (1,431 ) 576 Net income $ 44,244 $ 59,063 (1) Excludes costs which are included in determining SNOI. The Company's total assets by reportable segment as of March 31, 2017 and December 31, 2016 is as follows (in thousands): March 31, 2017 December 31, 2016 Carolinas/Richmond $ 510,910 $ 503,920 Chicago/Minnesota 613,095 616,298 Florida 515,539 514,431 Houston 528,071 530,438 Lehigh/Central PA 1,340,842 1,311,815 Philadelphia 585,797 557,510 Southeastern PA 265,353 262,155 United Kingdom 210,761 189,766 Other 1,428,459 1,403,431 Segment-level total assets 5,998,827 5,889,764 Corporate Other 85,074 103,049 Total assets $ 6,083,901 $ 5,992,813

Accounting for the Impairment o

Accounting for the Impairment or Disposal of Long-Lived Assets	3 Months Ended
	Mar. 31, 2017
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Asset Impairment Charges [Text Block]	Accounting for the Impairment or Disposal of Long-Lived Assets Asset Impairment The Company disposes of and anticipates the potential disposition of certain properties prior to the end of their remaining useful lives. There were no impairments recognized during the three months ended March 31, 2017 or 2016. The Company has evaluated each of its properties and land held for development and has determined that there were no valuation adjustments necessary at March 31, 2017 . In addition, the Company applied reasonable estimates and judgments in determining the level of impairments recognized. Should external or internal circumstances change requiring the need to shorten the holding periods or adjust the estimated future cash flows of the Company’s assets, the Company could be required to record impairment charges in the future.

Noncontrolling Interests of the

Noncontrolling Interests of the Trust	3 Months Ended
	Mar. 31, 2017
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 of the Operating Partnership not held by the Trust outstanding as of March 31, 2017 have the same economic characteristics as common shares of the Trust. The 3.5 million outstanding common units of the Operating Partnership 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 with unregistered common shares of the Trust. The market value of the 3.5 million outstanding common units based on the closing price of the common shares of the Trust at March 31, 2017 was $ 136.0 million .

Limited Partners' Equity of the

Limited Partners' Equity of the Operating Partnership	3 Months Ended
	Mar. 31, 2017
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 of the Operating Partnership not held by the Trust outstanding as of March 31, 2017 have the same economic characteristics as common shares of the Trust. The 3.5 million outstanding common units of the Operating Partnership 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 with unregistered common shares of the Trust. The market value of the 3.5 million outstanding common units based on the closing price of the common shares of the Trust at March 31, 2017 was $ 136.0 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 3.5 million outstanding common units as of March 31, 2017 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 with unregistered common shares of the Trust. The market value of the 3.5 million outstanding common units at March 31, 2017 based on the closing price of the common shares of the Trust at March 31, 2017 was $ 136.0 million .

Noncontrolling Interest - Opera

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units	3 Months Ended
	Mar. 31, 2017
Temporary Equity [Line Items]
Stockholders' Equity Note Disclosure [Text Block]	Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units As of March 31, 2017 , 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.

Disclosure of Fair Value of Fin

Disclosure of Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2017
Debt Instrument, Fair Value Disclosure [Abstract]
Disclosure of Fair Value of Financial Instruments	Fair Value of Financial Instruments ASC 820, Fair Value Measurements and Disclosures, gives guidance on the fair value measurement of a financial asset or liability. Inputs used to develop fair value are classified in one of three categories: Level 1 inputs (quoted prices (unadjusted) in active markets for identical assets or liabilities), Level 2 inputs (inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly) and Level 3 inputs (unobservable inputs for the asset or liability). 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 March 31, 2017 and December 31, 2016 . 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 March 31, 2017 and December 31, 2016 . 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, 2016 and March 31, 2017 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2016 $ 276,650 $ 286,684 $ 2,280,286 $ 2,340,762 As of March 31, 2017 $ 274,260 $ 285,263 $ 2,280,970 $ 2,365,887

Unconsolidated Joint Ventures

Unconsolidated Joint Ventures	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Unconsolidated Joint Ventures Cambridge Medipark Ltd During the three months ended March 31, 2017 and 2016, Cambridge Medipark, Ltd (a joint venture in which the Company holds a 50% interest) recognized gains and losses, respectively, on the sale of land leasehold interests. The Company's share of these gains/losses was a $3.0 million gain for the three months ended March 31, 2017 compared to a loss of $106,000 for the same period in 2016.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2017
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. The Company's interest rate risk management objectives are to limit generally the impact of interest rate changes on earnings and cash flows and to lower the Company's overall borrowing costs. To achieve these objectives, from time to time, the Company enters 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. The Company generally does not hold or issue these derivative contracts for trading or speculative purposes. The interest rate on all of the Company's 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 an 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 $98.2 million and $98.9 million at March 31, 2017 and December 31, 2016 , 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 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 months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 March 31, 2016 Amount of gain (loss) related to the effective portion recognized in other comprehensive loss $ 138 $ (1,643 ) Amount of loss related to the effective portion subsequently reclassified to interest expense $ (186 ) $ (283 ) Amount of gain (loss) related to the ineffective portion recognized in interest expense $ 22 $ (56 ) The fair value of the Swaps in the amounts of $4.1 million and $4.9 million as of March 31, 2017 and December 31, 2016 , respectively, is included in other liabilities in the accompanying consolidated balance sheets. The Company estimates that $0.3 million will be reclassified from accumulated other comprehensive loss 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, which totaled approximately $4.1 million as of March 31, 2017 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 , were as follows (in thousands): Year Amount 2017 (remaining) $ 1,290 2018 1,604 2019 1,604 2020 1,604 2021 1,604 2022 and thereafter 34,613 Total $ 42,319 Operating ground lease expense for the three months ended March 31, 2017 was $311,000 as compared to $256,000 for the same period in 2016 . 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 March 31, 2017 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 March 31, 2017 , the Company had letter of credit obligations of $6.9 million . As of March 31, 2017 , the Company had 28 buildings under development. These buildings are expected to contain, when completed, a total of 6.2 million square feet of leasable space and represent an anticipated aggregate investment of $601.4 million . At March 31, 2017 , development in progress totaled $321.3 million . In addition, as of March 31, 2017 , the Company had invested $11.1 million in deferred leasing costs related to these development buildings. As of March 31, 2017 , the Company was committed to $12.5 million in improvements on certain buildings and land parcels. As of March 31, 2017 , the Company was committed to $17.4 million in future land acquisitions and $19.1 million in future building acquisitions. The Company expects to complete these purchases during the year ended December 31, 2017. As of March 31, 2017 , the Company was obligated to pay for tenant improvements not yet completed for a maximum of $19.3 million . As of March 31, 2017 , the Company was committed to fund up to $4.0 million for tenant improvements and leasing commissions under a loan to the buyer of certain of the Company's properties. Unconsolidated joint ventures in which the Company holds an interest, and in another case an unrelated third party, have engaged the Company as the developer of its development properties pursuant to development agreements. The Company agrees, in consideration for a development fee, to be responsible for all aspects of the development of the properties and to guarantee the timely lien-free completion of construction of the properties and the payment, subject to certain exceptions, of any cost overruns incurred in the development of the properties. The Company is currently developing three buildings for its unconsolidated joint ventures which represent an anticipated aggregate investment by the joint ventures of $966.7 million . As of March 31, 2017, the Company was also committed to approximately $169.4 million in costs related to its agreement to develop, on a fee basis, an office building and infrastructure improvements for American Water Works in Camden, New Jersey. As of March 31, 2017, $32.9 million of these costs had been incurred. 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	3 Months Ended
	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure to Statements of Cash Flows	Supplemental Disclosure to Consolidated Statements of Cash Flows The following are supplemental disclosures to the consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 (amounts in thousands): 2017 2016 Write-off of fully depreciated/amortized property and deferred costs $ 12,280 $ 12,685 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 2,506 $ 32,323 Redemption of noncontrolling interests - common units $ 27 $ — Unrealized gain (loss) on cash flow hedge $ 313 $ (1,360 ) Changes in accrued development capital expenditures $ 7,421 $ 394 Capitalized equity-based compensation $ 604 $ 569 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.

Organization and Basis of Pre22

Organization and Basis of Presentation (Policy)	3 Months Ended
	Mar. 31, 2017
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 (except revenue in the scope of other accounting standards, including standards related to leasing). The standard clarifies the required factors that an entity must consider when recognizing revenue and requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. The standard also provides guidance regarding the measurement of gains and losses relative to the sale of certain nonfinancial assets, including real estate. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company has performed an initial assessment of ASU 2014-09 and plans to adopt the standard using the modified retrospective approach. Upon adoption of ASU 2016-02 (see below), the majority of our revenue will be subject to the allocation provisions outlined within the revenue standard. The Company is currently evaluating the specific implementation requirements for allocating the consideration within our contracts in accordance with ASU 2014-09 as well as other transactions subject to ASU 2014-09. The Company does not expect the new standard to have a material impact on the measurement and recognition of gains and losses on the sale of properties. In February 2016, the FASB issued ASU 2016-02, Leases ("ASU 2016-02"). ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 is effective for the Company beginning January 1, 2019. Early adoption of ASU 2016-02 is permitted. The standard requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. For leases in which the Company is the lessor, the standard requires that the lease and non-lease components of the lease agreement should be separated. Revenue related to the lease component of the contract will be recognized on a straight-line basis, while revenue related to the non-lease component will be recognized under the provisions of ASU 2014-09 (see above). For lease agreements longer than one year in which the Company is the lessee, the Company will measure the present value of the future lease payments and recognize a right-of-use asset and corresponding lease liability on its balance sheet. In addition, the new standard states that only direct leasing costs may be capitalized. The Company is evaluating the impact ASU 2016-02 will have on its financial position and results of operations. In March 2016, the FASB issued ASU 2016-05, Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships ("ASU 2016-05"). ASU 2016-05 states that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under FASB Topic 815 does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. ASU 2016-05 is effective for the Company beginning January 1, 2017. The Company adopted the standard on a prospective basis. The adoption of ASU 2016-05 did not have a material impact on the Company's financial position or results of operations. In March 2016, the FASB issued ASU 2016-09. ASU 2016-09 is designed to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Certain amendments in the standard are applied retrospectively and certain amendments are applied prospectively. The adoption of ASU 2016-09 did not have a material impact on the Company's financial position or results of operations. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 is designed to clarify how entities should classify cash receipts and cash payments in the statement of cash flows. ASU 2016-15 is effective for the Company beginning January 1, 2018. Early adoption of ASU 2016-15 is permitted. The standard requires retrospective application unless it is impracticable to do so. The Company is evaluating the impact ASU 2016-15 will have on its statement of cash flows. In February 2017, the FASB issued ASU 2017-05 Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets ("ASU 2017-05"). ASU 2017-05 is designed to provide guidance on how to recognize gain and losses on sales, including partial sale, of nonfinancial assets to noncustomers. ASU 2017-05 is effective for the Company beginning January 1, 2018. Early adoption is permitted but the standard is required to be adopted concurrently with ASU 2014-09. The Company is evaluating the impact ASU 2017-05 will have on the Company's financial position and results of operations.

Organization and Basis of Pre23

Organization and Basis of Presentation Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2017
Basis of Presentation [Abstract]
Schedule of Adjustments to Previously Reported Financial Statements	Previously, development service fee income relating to its unconsolidated joint ventures had been classified as other income and development service fee expense had been classified as general and administrative expense in amounts as follows: Three months ended March 31, 2016 Other income $ 1,372 General and administrative $ 1,098

Income per Common Share of th24

Income per Common Share of the Trust (Tables)	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 43,032 146,471 $ 0.29 $ 57,554 146,071 $ 0.39 Dilutive shares for long-term compensation plans — 750 — 460 Net income available to common shareholders - diluted $ 43,032 147,221 $ 0.29 $ 57,554 146,531 $ 0.39

Income per Common Unit of the25

Income per Common Unit of the Operating Partnership (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Unit, 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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 43,032 146,471 $ 0.29 $ 57,554 146,071 $ 0.39 Dilutive shares for long-term compensation plans — 750 — 460 Net income available to common shareholders - diluted $ 43,032 147,221 $ 0.29 $ 57,554 146,531 $ 0.39
Liberty Property Limited Partnership [Member]
Earnings Per Unit, 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 March 31, 2017 March 31, 2016 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 44,181 $ 59,063 Less: Preferred unit distributions (118 ) (118 ) Income available to common unitholders - basic $ 44,063 150,000 $ 0.29 $ 58,945 149,610 $ 0.39 Dilutive units for long-term compensation plans — 750 — 460 Income available to common unitholders - diluted $ 44,063 150,750 $ 0.29 $ 58,945 150,070 $ 0.39

Accumulated Other Comprehensi26

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2017
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 Loss (in thousands): As of and for the three months ended March 31, 2017 2016 Foreign Currency Translation: Beginning balance $ (56,767 ) $ (17,256 ) Translation adjustment 3,177 (5,087 ) Ending balance (53,590 ) (22,343 ) Derivative Instruments: Beginning balance (455 ) (865 ) Unrealized gain (loss) 127 (1,643 ) Reclassification adjustment (1) 186 283 Ending balance (142 ) (2,225 ) Total accumulated other comprehensive loss (53,732 ) (24,568 ) Less: portion included in noncontrolling interest – operating partnership 1,110 380 Total accumulated other comprehensive loss included in shareholders' equity/owners' equity $ (52,622 ) $ (24,188 ) (1) Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
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): Three Months Ended March 31, 2017 2016 Operating revenue Carolinas/Richmond $ 18,056 $ 15,760 Chicago/Minneapolis 15,875 21,539 Florida 14,248 29,318 Houston 14,774 14,766 Lehigh/Central PA 41,535 34,243 Philadelphia 11,436 10,355 Southeastern PA 14,615 25,883 United Kingdom 3,168 3,552 Other 30,372 34,998 Segment-level operating revenue 164,079 190,414 Reconciliation to total operating revenues Development service fee income 11,485 — Other (198 ) (274 ) Total operating revenue $ 175,366 $ 190,140 SNOI Carolinas/Richmond $ 12,982 $ 10,840 Chicago/Minneapolis 9,349 11,371 Florida 9,511 18,047 Houston 6,801 8,833 Lehigh/Central PA 29,578 24,202 Philadelphia 8,759 7,097 Southeastern PA 8,113 13,751 United Kingdom 1,858 2,405 Other 20,256 22,825 SNOI 107,207 119,371 Reconciliation to net income Interest expense (22,343 ) (31,412 ) Depreciation/amortization expense (1) (33,193 ) (39,798 ) Gain on property dispositions 807 20,521 Equity in earnings of unconsolidated joint ventures 5,731 4,914 General and administrative expense (1) (12,254 ) (14,539 ) Income taxes (1) (280 ) (570 ) Other (1,431 ) 576 Net income $ 44,244 $ 59,063 (1) Excludes costs which are included in determining SNOI.
Assets by Segment and Reconciliation to Consolidated[Table Text Block]	The Company's total assets by reportable segment as of March 31, 2017 and December 31, 2016 is as follows (in thousands): March 31, 2017 December 31, 2016 Carolinas/Richmond $ 510,910 $ 503,920 Chicago/Minnesota 613,095 616,298 Florida 515,539 514,431 Houston 528,071 530,438 Lehigh/Central PA 1,340,842 1,311,815 Philadelphia 585,797 557,510 Southeastern PA 265,353 262,155 United Kingdom 210,761 189,766 Other 1,428,459 1,403,431 Segment-level total assets 5,998,827 5,889,764 Corporate Other 85,074 103,049 Total assets $ 6,083,901 $ 5,992,813

Noncontrolling Interest - Ope28

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Tables)	3 Months Ended
	Mar. 31, 2017
Temporary Equity [Line Items]
Schedule of Temporary Equity [Table Text Block]	As of March 31, 2017 , 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 F29

Disclosure of Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2016 and March 31, 2017 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2016 $ 276,650 $ 286,684 $ 2,280,286 $ 2,340,762 As of March 31, 2017 $ 274,260 $ 285,263 $ 2,280,970 $ 2,365,887

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
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 months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 March 31, 2016 Amount of gain (loss) related to the effective portion recognized in other comprehensive loss $ 138 $ (1,643 ) Amount of loss related to the effective portion subsequently reclassified to interest expense $ (186 ) $ (283 ) Amount of gain (loss) related to the ineffective portion recognized in interest expense $ 22 $ (56 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 , were as follows (in thousands): Year Amount 2017 (remaining) $ 1,290 2018 1,604 2019 1,604 2020 1,604 2021 1,604 2022 and thereafter 34,613 Total $ 42,319

Supplemental Disclosure to St32

Supplemental Disclosure to Statements of Cash Flows (Tables)	3 Months Ended
	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure to Statements of Cash Flows	The following are supplemental disclosures to the consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 (amounts in thousands): 2017 2016 Write-off of fully depreciated/amortized property and deferred costs $ 12,280 $ 12,685 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 2,506 $ 32,323 Redemption of noncontrolling interests - common units $ 27 $ — Unrealized gain (loss) on cash flow hedge $ 313 $ (1,360 ) Changes in accrued development capital expenditures $ 7,421 $ 394 Capitalized equity-based compensation $ 604 $ 569

Organization and Basis of Pre33

Organization and Basis of Presentation (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Ownership interest in operating partnership - Limited Partnership	97.70%
Liberty Comcast 1701 JFK Boulevard, LP [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Liberty Comcast 1701 JFK Boulevard, LP [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Other Investments [Member]
Variable Interest Entity [Line Items]
Equity investment in joint venture	$ 18.2	$ 18.7
Maximum exposure to loss	$ 18.2	$ 18.7

Organization and Basis of Pre34

Organization and Basis of Presentation Prior period adjustments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Prior Period Adjustments [Line Items]
Cash outflow for shares related to tax withholdings	$ 4,624	$ 44,926
Development service fee expense	$ 11,004	0
Other Income [Member] | Scenario, Previously Reported [Member]
Prior Period Adjustments [Line Items]
Development service fee income		1,372
General and Administrative Expense [Member] | Scenario, Previously Reported [Member]
Prior Period Adjustments [Line Items]
Development service fee expense		1,098
Accounting Standards Update 2016-09 [Member] | Scenario, Previously Reported [Member]
Prior Period Adjustments [Line Items]
Cash outflow for shares related to tax withholdings		$ 4,000

Income per Common Share of th35

Income per Common Share of the Trust (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income (Numerator) [Abstract]
Net income available to common shareholders	$ 43,032	$ 57,554
Weighted Average Shares (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	146,471	146,071
Dilutive shares for long-term compensation plans	750	460
Weighted Average Number of Shares Outstanding, Diluted	147,221	146,531
Common shares [Member]
Earnings Per Share, Basic [Abstract]
Income per common share - basic	$ 0.29	$ 0.39
Earnings Per Share, Diluted [Abstract]
Income per common share - diluted	$ 0.29	$ 0.39

Income per Common Share of th36

Income per Common Share of the Trust Income per Common Share of the Trust - Anti-dilutive Options (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock Option [Member]
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	188,000	2,400,000

Income per Common Share of th37

Income per Common Share of the Trust - Options Exercised (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Stock Option [Member] | Common shares [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	11,000	369,000

Income per Common Share of th38

Income per Common Share of the Trust - Share Repurchase (Details) - Common shares [Member] - 2015 Share Repurchase Program [Member] shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)shares
Class of Stock [Line Items]
Authorized amount of shares available to be repurchased under a share repurchase plan | $	$ 250
Number of shares repurchased during period | shares	0

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
	Mar. 31, 2017	Mar. 31, 2016
Income (Numerator) [Abstract]
Net income available to common shareholders	$ 43,032	$ 57,554
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	146,471	146,071
Dilutive units for long-term compensation plans	750	460
Weighted Average Number of Shares Outstanding, Diluted	147,221	146,531
Liberty Property Limited Partnership [Member]
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 44,181	$ 59,063
Less: Preferred unit distributions	(118)	(118)
Net income available to common shareholders	$ 44,063	$ 58,945
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	150,000	149,610
Dilutive units for long-term compensation plans	750	460
Weighted Average Number of Shares Outstanding, Diluted	150,750	150,070
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Unit, Basic [Abstract]
Income per common share - basic	$ 0.29	$ 0.39
Earnings Per Unit, Diluted [Abstract]
Income per common share - diluted	$ 0.29	$ 0.39

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
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	188,000	2,400,000
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	188,000	2,400,000

Income per Common Unit of the41

Income per Common Unit of the Operations Partnership - Options Exercised (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Liberty Property Limited Partnership [Member] | Stock Option [Member] | Common Units [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	11,000	369,000

Income per Common Unit of the42

Income per Common Unit of the Operating Partnership - Unit Repurchase (Details) - 2015 Share Repurchase Program [Member] $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)shares
Common shares [Member]
Class of Stock [Line Items]
Authorized amount of shares available to be repurchased under a share repurchase plan | $	$ 250
Number of units repurchased during period | shares	0
Liberty Property Limited Partnership [Member] | Common Units [Member]
Class of Stock [Line Items]
Authorized amount of shares available to be repurchased under a share repurchase plan | $	$ 250
Number of units repurchased during period | shares	0

Accumulated Other Comprehensi43

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 3,062,923
Ending Balance		3,054,916
Total accumulated other comprehensive loss		3,062,923		$ 3,054,916	$ 3,062,923
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				2,995,841	3,003,391
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(56,767)	$ (17,256)
Unrealized loss		3,177	(5,087)
Ending Balance		(53,590)	(22,343)
Total accumulated other comprehensive loss		(56,767)	(17,256)	(53,590)	(56,767)	$ (22,343)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(455)	(865)
Unrealized loss		127	(1,643)
Reclassification adjustment	[1]	186	283
Ending Balance		(142)	(2,225)
Total accumulated other comprehensive loss		(455)	(865)	(142)	(455)	(2,225)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		(53,732)	(24,568)
Total accumulated other comprehensive loss		(53,732)	(24,568)	(53,732)		(24,568)
AOCI Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		1,110	380
Total accumulated other comprehensive loss		1,110	$ 380	1,110		380
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(56,031)
Ending Balance		(52,622)
Total accumulated other comprehensive loss		$ (56,031)		(52,622)	$ (56,031)
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				$ (52,622)		$ (24,188)
[1]	Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Assets Held for Sale (Details)

Assets Held for Sale (Details) - Florida [Member] - 2017 held for sale [Member] - Disposal Group, Held-for-sale, Not Discontinued Operations [Member] $ in Millions	Mar. 31, 2017USD ($)a
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a	16.4
Land held for development | $	$ 5

Building Acquisitions and Dispo

Building Acquisitions and Dispositions (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)ft²bldg	Mar. 31, 2016USD ($)
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Buildings and Land	$ 1,874	$ 127,727
Disposal Group, Not Discontinued Operations [Member] | 2017 sales [Member] | Operating Segments [Member] | Southeastern PA [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1
Net Rentable Area | ft²	33,000
Disposal Group, Not Discontinued Operations [Member] | 2017 sales [Member] | Operating Segments [Member] | Southeastern PA [Member] | Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Buildings and Land	$ 2,100

Performance of the Reportable S

Performance of the Reportable Segments Based on Property Level Operating Income (Details) - USD ($)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Operating revenue		$ 175,366,000	$ 190,140,000
Development service fee income		11,485,000	0
Net operating income		58,795,000	61,243,000
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense		(22,343,000)	(31,412,000)
Depreciation and amortization expense		(45,992,000)	(54,837,000)
Gain on property dispositions		807,000	20,521,000
Equity in earnings of unconsolidated joint ventures		5,731,000	4,914,000
General and administrative expense		(16,942,000)	(20,990,000)
Income taxes		(622,000)	(801,000)
Net income		44,244,000	59,063,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenue		0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenue		164,079,000	190,414,000
Net operating income		107,207,000	119,371,000
Operating Segments [Member] | Carolinas Richmond [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		18,056,000	15,760,000
Net operating income		12,982,000	10,840,000
Operating Segments [Member] | Chicago Minneapolis [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		15,875,000	21,539,000
Net operating income		9,349,000	11,371,000
Operating Segments [Member] | Florida [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		14,248,000	29,318,000
Net operating income		9,511,000	18,047,000
Operating Segments [Member] | Houston [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		14,774,000	14,766,000
Net operating income		6,801,000	8,833,000
Operating Segments [Member] | Lehigh Central PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		41,535,000	34,243,000
Net operating income		29,578,000	24,202,000
Operating Segments [Member] | Philadelphia [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		11,436,000	10,355,000
Net operating income		8,759,000	7,097,000
Operating Segments [Member] | Southeastern PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		14,615,000	25,883,000
Net operating income		8,113,000	13,751,000
Operating Segments [Member] | United Kingdom [Member] | UNITED KINGDOM
Segment Reporting Information [Line Items]
Operating revenue		3,168,000	3,552,000
Net operating income		1,858,000	2,405,000
Operating Segments [Member] | Other Segments [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		30,372,000	34,998,000
Net operating income		20,256,000	22,825,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenue		(198,000)	(274,000)
Development service fee income		11,485,000	0
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense		(22,343,000)	(31,412,000)
Depreciation and amortization expense	[1]	(33,193,000)	(39,798,000)
Gain on property dispositions		807,000	20,521,000
Equity in earnings of unconsolidated joint ventures		5,731,000	4,914,000
General and administrative expense	[1]	(12,254,000)	(14,539,000)
Income taxes	[1]	(280,000)	(570,000)
Other		$ (1,431,000)	$ 576,000
[1]	Excludes costs which are included in determining SNOI.

Segment Information Total Asset

Segment Information Total Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 6,083,901	$ 5,992,813
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	5,998,827	5,889,764
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	85,074	103,049
North America [Member] | Operating Segments [Member] | Carolinas Richmond [Member]
Segment Reporting Information [Line Items]
Assets	510,910	503,920
North America [Member] | Operating Segments [Member] | Chicago Minneapolis [Member]
Segment Reporting Information [Line Items]
Assets	613,095	616,298
North America [Member] | Operating Segments [Member] | Florida [Member]
Segment Reporting Information [Line Items]
Assets	515,539	514,431
North America [Member] | Operating Segments [Member] | Houston [Member]
Segment Reporting Information [Line Items]
Assets	528,071	530,438
North America [Member] | Operating Segments [Member] | Lehigh Central PA [Member]
Segment Reporting Information [Line Items]
Assets	1,340,842	1,311,815
North America [Member] | Operating Segments [Member] | Philadelphia [Member]
Segment Reporting Information [Line Items]
Assets	585,797	557,510
North America [Member] | Operating Segments [Member] | Southeastern PA [Member]
Segment Reporting Information [Line Items]
Assets	265,353	262,155
North America [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	1,428,459	1,403,431
UNITED KINGDOM | Operating Segments [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Assets	$ 210,761	$ 189,766

Accounting for the Impairment48

Accounting for the Impairment or Disposal of Long-Lived Assets Asset Impairment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Property, Plant and Equipment [Line Items]
Impairment - real estate assets	$ 0	$ 0

Noncontrolling Interests of t49

Noncontrolling Interests of the Trust- Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Redeemable Noncontrolling Interest [Line Items]
Limited Partners' common units outstanding	3,528,281	3,530,031
Market value of common units based on closing price	$ 136
Liberty Property Limited Partnership [Member]
Redeemable Noncontrolling Interest [Line Items]
Limited Partners' common units outstanding	3,528,281	3,530,031

Limited Partners' Equity of t50

Limited Partners' Equity of the Operating Partnership - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Limited Partners' Capital Account [Line Items]
Limited Partners' common units outstanding	3,528,281	3,530,031
Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Limited Partners' common units outstanding	3,528,281	3,530,031
market value of the outstanding common units	$ 136

Noncontrolling Interest - Ope51

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Temporary Equity [Line Items]
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of March 31, 2017 and December 31, 2016	$ 7,537	$ 7,537
Series I 2 [Member]
Temporary Equity [Line Items]
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of March 31, 2017 and December 31, 2016	$ 7,537
Units	301,483	301,483
Liquidation Preference	$ 25
Dividend Rate	6.25%

Disclosure of Fair Value of F52

Disclosure of Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loans	$ 274,260	$ 276,650
Unsecured Debt	2,280,970	2,280,286
Unsecured Debt [Member] | Fair Value, Inputs, Level 3 [Member] | Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	2,365,887	2,340,762
Mortgage Loans | Fair Value, Inputs, Level 3 [Member] | Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	$ 285,263	$ 286,684

Unconsolidated Joint Ventures (

Unconsolidated Joint Ventures (Details) - Cambridge Medipark Ltd [Member] - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Joint venture, 2017 sales current quarter [Member] | Gain on equity method investments [Member] | Disposal Group, Not Discontinued Operations [Member] | Leaseholds and Leasehold Improvements [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of leasehold interests	$ (3,000,000)
Joint venture, 2016 sales current quarter [Member] | Gain on equity method investments [Member] | Disposal Group, Not Discontinued Operations [Member] | Leaseholds and Leasehold Improvements [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of leasehold interests		$ 106,000

Derivative Instruments (Details

Derivative Instruments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Interest Rate Derivatives [Abstract]
Number of interest rate swap contracts	3
aggregate notional amount	$ 98,200		$ 98,900
Termination value of interest rate swap, including accrued interest	4,100
Interest Rate Cash Flow Hedges [Abstract]
Fair value of interest rate swaps	4,100		$ 4,900
Amount estimated to be reclassified from accumulated other comprehensive income as an increase to interest expense	300
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 loss	138	$ (1,643)
Interest Rate Swap [Member] | Interest Expense [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss related to the effective portion subsequently reclassified to interest expense	(186)	(283)
Amount of gain (loss) related to the ineffective portion recognized in interest expense	$ 22	$ (56)

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Rental Payments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
2017 (remaining)	$ 1,290,000
2,018	1,604,000
2,019	1,604,000
2,020	1,604,000
2,021	1,604,000
2022 and thereafter	34,613,000
Total	42,319,000
Other Expenses [Abstract]
Operating ground lease expense	$ 311,000	$ 256,000

Commitments and Contingencies56

Commitments and Contingencies - Loss Contingencies (Details) $ in Millions	Mar. 31, 2017USD ($)
Legal Matters [Abstract]
Loss Contingency, Pending Claims, Number	0
Other [Abstract]
Letter of credit obligations	$ 6.9
Contractual Obligation	$ 4

Commitments and Contingencies57

Commitments and Contingencies - Supply Commitments (Details) $ in Thousands, ft² in Millions	12 Months Ended
	Dec. 31, 2016USD ($)	Mar. 31, 2017USD ($)ft²bldgproperties
Supply Commitment [Line Items]
Development in progress	$ 267,450	$ 321,331
Construction in Progress [Member]
Supply Commitment [Line Items]
Net Rentable Area | ft²		6.2
Number of Real Estate Properties | properties		28
Total anticipated development cost		$ 601,400
Deferred leasing costs in development		11,100
Buildings and land parcels [Member]
Supply Commitment [Line Items]
Remaining amount committed or obligated to pay for the benefit of current or future tenants		12,500
Tenant Improvements [Member]
Supply Commitment [Line Items]
Tenant improvements not yet completed		$ 19,300
Equity Method Investments [Member] | Construction in Progress [Member] | Construction in Progress [Member]
Supply Commitment [Line Items]
Number of Real Estate Properties | bldg		3
Equity Method Investments [Member] | Buildings and land parcels [Member] | Construction in Progress [Member]
Supply Commitment [Line Items]
Total anticipated development cost		$ 966,700
American Water Works, Inc [Member] | Building and Building Improvements [Member]
Supply Commitment [Line Items]
Development for fee revenue	169,400
Cost of Real Estate Sales	$ 32,900

Commitments and Contingencies58

Commitments and Contingencies - Purchase Commitments (Details) - Land Purchases [Member] $ in Millions	Mar. 31, 2017USD ($)
Land and Land Improvements [Member]
Long-term Purchase Commitment [Line Items]
Remaining amount committed to future acquisitions	$ 17.4
Land, Buildings and Improvements [Member]
Long-term Purchase Commitment [Line Items]
Remaining amount committed to future acquisitions	$ 19.1

Supplemental Disclosure to St59

Supplemental Disclosure to Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Supplemental Cash Flow Information [Abstract]
Write-off of fully depreciated/amortized property and deferred costs	$ 12,280	$ 12,685
Write-off of depreciated/amortized property and deferred costs due to sale/demolition	2,506	32,323
Redemption of noncontrolling interests - common units	27	0
Unrealized gain (loss) on cash flow hedge	313	(1,360)
Changes in accrued development capital expenditures	7,421	394
Capitalized equity-based compensation	$ 604	$ 569