Liberty Property Limited Partnership 10-Q 4 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2016	Aug. 02, 2016
Entity Information [Line Items]
Entity Registrant Name	LIBERTY PROPERTY TRUST
Entity Central Index Key	921,112
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		146,738,052
Liberty Property Limited Partnership [Member]
Entity Information [Line Items]
Entity Registrant Name	LIBERTY PROPERTY LIMITED PARTNERSHIP
Entity Central Index Key	921,113

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Real Estate [Abstract]
Land and land improvements	$ 1,191,875	$ 1,182,366
Building and improvements	5,161,117	5,122,396
Less accumulated depreciation	(1,199,941)	(1,148,014)
Operating real estate	5,153,051	5,156,748
Development in progress	438,542	360,948
Land held for development	324,836	336,967
Net real estate	5,916,429	5,854,663
Cash and cash equivalents	29,340	35,353
Restricted cash	5,029	9,018
Accounts receivable	12,315	14,343
Deferred rent receivable	124,948	118,783
Deferred financing and leasing costs, net of accumulated amortization (June 30, 2016, $175,870; December 31, 2015, $175,023)	178,980	191,987
Investments in and advances to unconsolidated joint ventures	222,679	218,454
Assets held for sale	2,915	15,979
Prepaid expenses and other assets	92,233	99,049
Total assets	6,584,868	6,557,629
LIABILITIES
Mortgage loans	284,892	307,908
Unsecured notes	2,581,663	2,580,108
Credit facility	395,000	259,000
Accounts payable	67,585	51,382
Accrued interest	26,496	26,154
Dividend and distributions payable	71,363	71,787
Other liabilities	217,885	243,806
Total liabilities	3,644,884	3,540,145
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2016 and December 31, 2015	7,537	7,537
EQUITY
Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 146,716,684 and 147,577,984 shares issued and outstanding as of June 30, 2016 and December 31, 2015, respectively	147	148
Additional paid-in capital	3,645,432	3,669,627
Accumulated other comprehensive loss	(37,803)	(17,893)
Distributions in excess of net income	(730,959)	(698,954)
Total Liberty Property Trust shareholders' equity	2,876,817	2,952,928
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	51,711	53,100
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total owners' equity	2,932,447	3,009,947
Total liabilities, noncontrolling interest - operating partnership and equity	6,584,868	6,557,629
Liberty Property Limited Partnership [Member]
Real Estate [Abstract]
Land and land improvements	1,191,875	1,182,366
Building and improvements	5,161,117	5,122,396
Less accumulated depreciation	(1,199,941)	(1,148,014)
Operating real estate	5,153,051	5,156,748
Development in progress	438,542	360,948
Land held for development	324,836	336,967
Net real estate	5,916,429	5,854,663
Cash and cash equivalents	29,340	35,353
Restricted cash	5,029	9,018
Accounts receivable	12,315	14,343
Deferred rent receivable	124,948	118,783
Deferred financing and leasing costs, net of accumulated amortization (June 30, 2016, $175,870; December 31, 2015, $175,023)	178,980	191,987
Investments in and advances to unconsolidated joint ventures	222,679	218,454
Assets held for sale	2,915	15,979
Prepaid expenses and other assets	92,233	99,049
Total assets	6,584,868	6,557,629
LIABILITIES
Mortgage loans	284,892	307,908
Unsecured notes	2,581,663	2,580,108
Credit facility	395,000	259,000
Accounts payable	67,585	51,382
Accrued interest	26,496	26,154
Dividend and distributions payable	71,363	71,787
Other liabilities	217,885	243,806
Total liabilities	3,644,884	3,540,145
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2016 and December 31, 2015	7,537	7,537
EQUITY
General partner’s equity - 146,716,684 and 147,577,984 common units outstanding as of June 30, 2016 and December 31, 2015, respectively	2,876,817	2,952,928
Limited partners' equity	51,711	53,100
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total owners' equity	2,932,447	3,009,947
Total liabilities, noncontrolling interest - operating partnership and equity	$ 6,584,868	$ 6,557,629

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Deferred financing and leasing costs, accumulated amortization	$ 175,870,000	$ 175,023,000
Limited Partners' common units outstanding	3,539,075	3,539,075
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	146,716,684	147,577,984
Common shares of beneficial interest, shares outstanding	146,716,684	147,577,984
Liberty Property Limited Partnership [Member]
Deferred financing and leasing costs, accumulated amortization	$ 175,870,000	$ 175,023,000
Limited Partners' common units outstanding	3,539,075	3,539,075
Common shares of beneficial interest, shares outstanding	146,716,684	147,577,984
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	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
OPERATING REVENUE
Rental	$ 139,143,000	$ 147,367,000	$ 278,198,000	$ 295,952,000
Operating expense reimbursement	47,511,000	56,151,000	98,597,000	114,467,000
Total operating revenue	186,654,000	203,518,000	376,795,000	410,419,000
OPERATING EXPENSE
Rental property	24,745,000	31,949,000	53,255,000	67,520,000
Real estate taxes	25,202,000	26,462,000	50,522,000	52,626,000
General and administrative	15,629,000	17,053,000	36,619,000	35,855,000
Depreciation and amortization	53,545,000	56,833,000	107,623,000	115,629,000
Impairment - real estate assets	0	1,036,000	0	16,775,000
Total operating expenses	119,121,000	133,333,000	248,019,000	288,405,000
Operating income	67,533,000	70,185,000	128,776,000	122,014,000
OTHER INCOME (EXPENSE)
Interest and other income	4,992,000	6,581,000	9,590,000	12,952,000
Interest expense	(30,131,000)	(35,066,000)	(61,543,000)	(69,736,000)
Total other income (expense)	(25,139,000)	(28,485,000)	(51,953,000)	(56,784,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	42,394,000	41,700,000	76,823,000	65,230,000
Gain on property dispositions	3,832,000	1,249,000	24,353,000	3,520,000
Income taxes	(752,000)	(1,169,000)	(1,553,000)	(2,014,000)
Equity in earnings (loss) of unconsolidated joint ventures	5,583,000	(5,254,000)	10,497,000	1,652,000
Income from continuing operations	51,057,000	36,526,000	110,120,000	68,388,000
Net income	51,057,000	36,526,000	110,120,000	68,388,000
Noncontrolling interest – operating partnership	(1,317,000)	(958,000)	(2,826,000)	(1,811,000)
Noncontrolling interest - consolidated joint ventures	(113,000)	(55,000)	(113,000)	(113,000)
Net income available to common shareholders	49,627,000	35,513,000	107,181,000	66,464,000
Comprehensive income attributable to common shareholders
Net income	51,057,000	36,526,000	110,120,000	68,388,000
Other comprehensive (loss) gain - foreign currency translation	(13,509,000)	12,151,000	(18,596,000)	1,741,000
Other comprehensive (loss) gain - derivative instruments	(435,000)	628,000	(1,795,000)	(319,000)
Other comprehensive (loss) gain	(13,944,000)	12,779,000	(20,391,000)	1,422,000
Total comprehensive income	37,113,000	49,305,000	89,729,000	69,810,000
Less: comprehensive income attributable to noncontrolling interest	(1,101,000)	(1,309,000)	(2,458,000)	(1,957,000)
Comprehensive income attributable to common shareholders	$ 36,012,000	$ 47,996,000	$ 87,271,000	$ 67,853,000
Weighted average number of common shares outstanding
Basic	145,995	148,778	146,002	148,574
Diluted	146,735	149,454	146,622	149,247
Amounts attributable to common shareholders
Net income available to common shareholders	$ 49,627,000	$ 35,513,000	$ 107,181,000	$ 66,464,000
Liberty Property Limited Partnership [Member]
OPERATING REVENUE
Rental	139,143,000	147,367,000	278,198,000	295,952,000
Operating expense reimbursement	47,511,000	56,151,000	98,597,000	114,467,000
Total operating revenue	186,654,000	203,518,000	376,795,000	410,419,000
OPERATING EXPENSE
Rental property	24,745,000	31,949,000	53,255,000	67,520,000
Real estate taxes	25,202,000	26,462,000	50,522,000	52,626,000
General and administrative	15,629,000	17,053,000	36,619,000	35,855,000
Depreciation and amortization	53,545,000	56,833,000	107,623,000	115,629,000
Impairment - real estate assets	0	1,036,000	0	16,775,000
Total operating expenses	119,121,000	133,333,000	248,019,000	288,405,000
Operating income	67,533,000	70,185,000	128,776,000	122,014,000
OTHER INCOME (EXPENSE)
Interest and other income	4,992,000	6,581,000	9,590,000	12,952,000
Interest expense	(30,131,000)	(35,066,000)	(61,543,000)	(69,736,000)
Total other income (expense)	(25,139,000)	(28,485,000)	(51,953,000)	(56,784,000)
Income before gain on property dispositions, income taxes and equity in earnings (loss) of unconsolidated joint ventures	42,394,000	41,700,000	76,823,000	65,230,000
Gain on property dispositions	3,832,000	1,249,000	24,353,000	3,520,000
Income taxes	(752,000)	(1,169,000)	(1,553,000)	(2,014,000)
Equity in earnings (loss) of unconsolidated joint ventures	5,583,000	(5,254,000)	10,497,000	1,652,000
Net income	51,057,000	36,526,000	110,120,000	68,388,000
Noncontrolling interest - consolidated joint ventures	(113,000)	(55,000)	(113,000)	(113,000)
Preferred unit distributions	(118,000)	(118,000)	(236,000)	(236,000)
Net income available to common shareholders	50,826,000	36,353,000	109,771,000	68,039,000
Comprehensive income attributable to common shareholders
Net income	51,057,000	36,526,000	110,120,000	68,388,000
Other comprehensive (loss) gain - foreign currency translation	(13,509,000)	12,151,000	(18,596,000)	1,741,000
Other comprehensive (loss) gain - derivative instruments	(435,000)	628,000	(1,795,000)	(319,000)
Other comprehensive (loss) gain	(13,944,000)	12,779,000	(20,391,000)	1,422,000
Total comprehensive income	$ 37,113,000	$ 49,305,000	$ 89,729,000	$ 69,810,000
Weighted average number of common shares outstanding
Basic	149,534	152,317	149,541	152,114
Diluted	150,274	152,993	150,161	152,787
Net income allocated to general partners	$ 49,627,000	$ 35,513,000	$ 107,181,000	$ 66,464,000
Net income allocated to limited partners	1,317,000	958,000	2,826,000	1,811,000
Amounts attributable to common shareholders
Income from continuing operations	50,944,000	36,471,000	110,007,000	68,275,000
Net income available to common shareholders	$ 50,826,000	$ 36,353,000	$ 109,771,000	$ 68,039,000
Common shares [Member]
Basic:
Income per common share - basic	$ 0.34	$ 0.24	$ 0.73	$ 0.45
Diluted:
Income per common share - diluted	0.34	0.24	0.73	0.45
Distributions per common share or unit	0.475	0.475	0.95	0.95
Common Units [Member] | Liberty Property Limited Partnership [Member]
Basic:
Income per common share - basic	0.34	0.24	0.73	0.45
Diluted:
Income per common share - diluted	0.34	0.24	0.73	0.45
Distributions per common share or unit	$ 0.475	$ 0.475	$ 0.95	$ 0.95

Consolidated Statement of Equit

Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Common Shares Of Beneficial Interest [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Distributions in Excess of Net Income [Member]	Total Liberty Property Trust Shareholders' Equity [Member]	Noncontrolling interest operating partnership Common [Member]	Noncontrolling interest-consolidated joint ventures [Member]	Total Equity [Member]	Liberty Property Limited Partnership [Member]	Liberty Property Limited Partnership [Member]General Partners Equity [Member]	Liberty Property Limited Partnership [Member]Limited Partners' Equity - Common Units [Member]	Liberty Property Limited Partnership [Member]Noncontrolling interest-consolidated joint ventures [Member]	Liberty Property Limited Partnership [Member]Total Equity [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 68,388									$ 68,388
Other comprehensive loss - foreign currency translation	1,741									1,741
Other comprehensive loss - derivative instruments	(319)									(319)
Beginning Balance at Dec. 31, 2015	3,009,947	$ 148	$ 3,669,627	$ (17,893)	$ (698,954)	$ 2,952,928	$ 53,100	$ 3,919	$ 3,009,947	3,009,947	$ 2,952,928	$ 53,100	$ 3,919	$ 3,009,947
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from the issuance of common shares			4,341			4,341			4,341
Net income	110,120				107,181	107,181	2,590	113	109,884	110,120	107,181	2,590	113	109,884
Contributions from partners											16,702			16,702
Distributions					(139,188)	(139,188)	(3,498)	(113)	(142,799)
Distributions to partners											(139,188)	(3,498)	(113)	(142,799)
Share/Unit repurchase		(1)	(40,895)			(40,896)			(40,896)		(40,896)			(40,896)
Share-based compensation			12,361			12,361			12,361
Other comprehensive loss - foreign currency translation	(18,596)			(18,157)		(18,157)	(439)		(18,596)	(18,596)	(18,157)	(439)		(18,596)
Other comprehensive loss - derivative instruments	(1,795)			(1,753)		(1,753)	(42)		(1,795)	(1,795)	(1,753)	(42)		(1,795)
Ending Balance at Jun. 30, 2016	2,932,447	$ 147	$ 3,645,434	$ (37,803)	$ (730,961)	$ 2,876,817	$ 51,711	$ 3,919	$ 2,932,447	2,932,447	$ 2,876,817	$ 51,711	$ 3,919	$ 2,932,447
Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance at Dec. 31, 2015	7,537									7,537
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (Mezzanine)	236									236
Distributions (Mezzanine)	(236)									(236)
Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance at Jun. 30, 2016	$ 7,537									$ 7,537

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING ACTIVITIES
Net income	$ 110,120,000	$ 68,388,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	109,047,000	117,160,000
Amortization of deferred financing costs	2,004,000	2,168,000
Impairment - real estate assets	0	16,775,000
Equity in earnings of unconsolidated joint ventures	(10,497,000)	(1,652,000)
Distributions from unconsolidated joint ventures	0	4,441,000
Gain on property dispositions	(24,353,000)	(3,520,000)
Share-based compensation/Non-cash compensation	11,553,000	9,504,000
Other	(4,424,000)	(6,750,000)
Changes in operating assets and liabilities:
Restricted cash	3,390,000	2,541,000
Accounts receivable	1,794,000	665,000
Deferred rent receivable	(8,897,000)	(11,319,000)
Prepaid expenses and other assets	312,000	(16,540,000)
Accounts payable	3,877,000	(5,647,000)
Accrued interest	342,000	2,663,000
Other liabilities	(17,342,000)	(5,780,000)
Net cash provided by operating activities	176,926,000	173,097,000
INVESTING ACTIVITIES
Investment in properties - acquisitions	(8,000,000)	(36,714,000)
Investment in properties - other	(30,338,000)	(33,585,000)
Investments in and advances to unconsolidated joint ventures	(31,372,000)	(17,182,000)
Distributions from unconsolidated joint ventures	35,250,000	7,979,000
Net proceeds from disposition of properties/land	139,814,000	156,891,000
Investment in development in progress	(175,744,000)	(78,120,000)
Investment in land held for development	(36,855,000)	(23,150,000)
Payment of deferred leasing costs	(15,057,000)	(23,395,000)
Investing - Other	7,842,000	5,154,000
Net cash used in investing activities	(114,460,000)	(42,122,000)
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	4,341,000	25,227,000
Share repurchase	40,896,000	0
Proceeds from unsecured notes	0	398,576,000
Repayment of unsecured notes	0	(300,000,000)
Repayments of mortgage loans	(22,123,000)	(4,567,000)
Proceeds from credit facility	338,300,000	613,200,000
Repayments on credit facility	(202,300,000)	(710,200,000)
Payment of deferred financing costs	0	(3,551,000)
Distribution paid on common shares	(139,742,000)	(141,395,000)
Distribution paid on units	(3,847,000)	(3,821,000)
Net cash used in financing activities	(66,267,000)	(126,531,000)
Net (decrease) increase in cash and cash equivalents	(3,801,000)	4,444,000
Decrease in cash and cash equivalents related to foreign currency translation	(2,212,000)	(737,000)
Cash and cash equivalents at beginning of period	35,353,000	69,346,000
Cash and cash equivalents at end of period	29,340,000	73,053,000
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	110,120,000	68,388,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	109,047,000	117,160,000
Amortization of deferred financing costs	2,004,000	2,168,000
Impairment - real estate assets	0	16,775,000
Equity in earnings of unconsolidated joint ventures	(10,497,000)	(1,652,000)
Distributions from unconsolidated joint ventures	0	4,441,000
Gain on property dispositions	(24,353,000)	(3,520,000)
Share-based compensation/Non-cash compensation	11,553,000	9,504,000
Other	(4,424,000)	(6,750,000)
Changes in operating assets and liabilities:
Restricted cash	3,390,000	2,541,000
Accounts receivable	1,794,000	665,000
Deferred rent receivable	(8,897,000)	(11,319,000)
Prepaid expenses and other assets	312,000	(16,540,000)
Accounts payable	3,877,000	(5,647,000)
Accrued interest	342,000	2,663,000
Other liabilities	(17,342,000)	(5,780,000)
Net cash provided by operating activities	176,926,000	173,097,000
INVESTING ACTIVITIES
Investment in properties - acquisitions	(8,000,000)	(36,714,000)
Investment in properties - other	(30,338,000)	(33,585,000)
Investments in and advances to unconsolidated joint ventures	(31,372,000)	(17,182,000)
Distributions from unconsolidated joint ventures	35,250,000	7,979,000
Net proceeds from disposition of properties/land	139,814,000	156,891,000
Investment in development in progress	(175,744,000)	(78,120,000)
Investment in land held for development	(36,855,000)	(23,150,000)
Payment of deferred leasing costs	(15,057,000)	(23,395,000)
Investing - Other	7,842,000	5,154,000
Net cash used in investing activities	(114,460,000)	(42,122,000)
FINANCING ACTIVITIES
Proceeds from unsecured notes	0	398,576,000
Repayment of unsecured notes	0	(300,000,000)
Repayments of mortgage loans	(22,123,000)	(4,567,000)
Proceeds from credit facility	338,300,000	613,200,000
Repayments on credit facility	(202,300,000)	(710,200,000)
Payment of deferred financing costs	0	(3,551,000)
Capital contributions	4,341,000	25,227,000
Distributions to partners	(184,485,000)	(145,216,000)
Net cash used in financing activities	(66,267,000)	(126,531,000)
Net (decrease) increase in cash and cash equivalents	(3,801,000)	4,444,000
Decrease in cash and cash equivalents related to foreign currency translation	(2,212,000)	(737,000)
Cash and cash equivalents at beginning of period	35,353,000	69,346,000
Cash and cash equivalents at end of period	$ 29,340,000	$ 73,053,000

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2016
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 97.6% of the common equity of the Operating Partnership at June 30, 2016 . 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. As of January 1, 2016 under the revised accounting standard Topic 810 (see Recently Issued Accounting Standards below), 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 97.6% 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 $19.8 million and $20.5 million as of June 30, 2016 and December 31, 2015, 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, 2015 . In the opinion of management, all adjustments (consisting solely of normal recurring adjustments) necessary for a fair presentation of the financial statements for these interim periods have been included. The results of interim periods are not necessarily indicative of the results to be obtained for a full fiscal year. Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which supersedes nearly all existing revenue recognition guidance. The standard clarifies the required factors that an entity must consider when recognizing revenue. The standard also requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company is evaluating the impact ASU 2014-09 will have on its financial position and results of operations and has not yet selected a transition method. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis (Topic 810) ("ASU 2015-02"). The standard requires that all entities re-evaluate and revise consolidation documentation for limited partnerships and similar legal entities. It makes changes to both the variable interest model and voting model. The Company adopted ASU 2015-02 beginning January 1, 2016. The adoption of ASU 2015-02 did not have a material impact on the Company's financial position and results of operations. 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. 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. Early adoption of ASU 2016-05 is permitted. The standard allows application on a prospective or modified retrospective basis. The Company does not believe that ASU 2016-05 will have a material impact on its financial position and results of operations. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting ("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. ASU 2016-09 is effective for the Company beginning January 1, 2017. Early adoption of ASU 2016-09 is permitted. Certain amendments in the standard are to be applied retrospectively and certain amendments are to be applied prospectively. The Company is evaluating the impact ASU 2016-09 will have on its financial position and results of operations.

Income per Common Share of the

Income per Common Share of the Trust	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Income per Common Share of the Trust The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 49,627 145,995 $ 0.34 $ 35,513 148,778 $ 0.24 Dilutive shares for long-term compensation plans — 740 — 676 Net income available to common shareholders - diluted $ 49,627 146,735 $ 0.34 $ 35,513 149,454 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 107,181 146,002 $ 0.73 $ 66,464 148,574 $ 0.45 Dilutive shares for long-term compensation plans — 620 — 673 Net income available to common shareholders - diluted $ 107,181 146,622 $ 0.73 $ 66,464 149,247 $ 0.45 Dilutive shares for long-term compensation plans represent the unvested common shares outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common share for the three and six months ended June 30, 2016 was 885,000 and 1,668,000 , respectively, as compared to 1,528,000 and 1,448,000 , respectively, for the same periods in 2015 . During the three and six months ended June 30, 2016 , 97,000 and 112,000 common shares, respectively, were issued upon the exercise of options. During the year ended December 31, 2015 , 65,000 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 will 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. During the three months ended March 31, 2016, the Company purchased an aggregate of 1.4 million common shares for $40.9 million at an average price of $29.28 per share as part of the share repurchase plan. There were no such purchases during the three months ended June 30, 2016.

Income per Common Unit of the O

Income per Common Unit of the Operating Partnership	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 49,627 145,995 $ 0.34 $ 35,513 148,778 $ 0.24 Dilutive shares for long-term compensation plans — 740 — 676 Net income available to common shareholders - diluted $ 49,627 146,735 $ 0.34 $ 35,513 149,454 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 107,181 146,002 $ 0.73 $ 66,464 148,574 $ 0.45 Dilutive shares for long-term compensation plans — 620 — 673 Net income available to common shareholders - diluted $ 107,181 146,622 $ 0.73 $ 66,464 149,247 $ 0.45 Dilutive shares for long-term compensation plans represent the unvested common shares outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common share for the three and six months ended June 30, 2016 was 885,000 and 1,668,000 , respectively, as compared to 1,528,000 and 1,448,000 , respectively, for the same periods in 2015 . During the three and six months ended June 30, 2016 , 97,000 and 112,000 common shares, respectively, were issued upon the exercise of options. During the year ended December 31, 2015 , 65,000 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 will 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. During the three months ended March 31, 2016, the Company purchased an aggregate of 1.4 million common shares for $40.9 million at an average price of $29.28 per share as part of the share repurchase plan. There were no such purchases during the three months ended June 30, 2016.
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 June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 50,944 $ 36,471 Less: Preferred unit distributions (118 ) (118 ) Income available to common unitholders - basic $ 50,826 149,534 $ 0.34 $ 36,353 152,317 $ 0.24 Dilutive units for long-term compensation plans — 740 — 676 Income available to common unitholders - diluted $ 50,826 150,274 $ 0.34 $ 36,353 152,993 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 110,007 $ 68,275 Less: Preferred unit distributions (236 ) (236 ) Income available to common unitholders - basic 109,771 149,541 $ 0.73 68,039 152,114 $ 0.45 Dilutive units for long-term compensation plans — 620 — 673 Income available to common unitholders - diluted $ 109,771 150,161 $ 0.73 $ 68,039 152,787 $ 0.45 Dilutive units for long-term compensation plans represent the unvested common units outstanding during the periods as well as the dilutive effect of outstanding options. The amount of anti-dilutive options excluded from the computation of diluted income per common unit for the three and six months ended June 30, 2016 was 885,000 and 1,668,000 , respectively, as compared to 1,528,000 and 1,448,000 , respectively, for the same periods in 2015 . During the three and six months ended June 30, 2016 , 97,000 and 112,000 common units, respectively, were issued upon exercise of options. During the year ended December 31, 2015 , 65,000 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 will 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. During the three months ended March 31, 2016, the Company purchased an aggregate of 1.4 million common shares for $40.9 million at an average price of $29.28 per share as part of the share repurchase plan. In connection with these repurchases, an equal number of common units were repurchased by the Operating Partnership from the Trust. There were no such purchases during the three months ended June 30, 2016.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016 2015 Foreign Currency Translation: Beginning balance $ (17,256 ) $ (5,823 ) Translation adjustment (18,596 ) 1,741 Ending balance (35,852 ) (4,082 ) Derivative Instruments: Beginning balance (865 ) (377 ) Unrealized loss (2,354 ) (1,022 ) Reclassification adjustment (1) 559 703 Ending balance (2,660 ) (696 ) Total accumulated other comprehensive loss (38,512 ) (4,778 ) Less: portion included in noncontrolling interest – operating partnership 709 (85 ) Total accumulated other comprehensive loss included in shareholders' equity/owners' equity $ (37,803 ) $ (4,863 ) (1) Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016, the Company realigned its reportable segments as follows: • Carolinas/Richmond; • Chicago/Milwaukee; • Florida; • Houston; • Lehigh/Central PA; • Minnesota; • 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; Northern Virginia; Southern California; and other. Comparative prior periods have been restated to reflect current segment disclosures. The Company evaluates the performance of its reportable segments based on net operating income. Net operating income includes operating revenue from external customers, real estate taxes, amortization of lease transaction costs and other operating expenses which relate directly to the management and operation of the assets within each reportable segment. The Company's accounting policies for the segments are the same as those used in the Company's consolidated financial statements. There are no material inter-segment transactions. The operating information by reportable segment is as follows (in thousands): Three Months Six Months Ended June 30, Ended June 30, 2016 2015 2016 2015 Operating revenue Carolinas/Richmond $ 16,174 $ 20,212 $ 31,934 $ 40,547 Chicago/Milwaukee 10,319 8,931 20,512 18,724 Florida 27,798 31,424 57,115 62,358 Houston 14,204 13,151 28,971 25,474 Lehigh/Central PA 33,782 32,844 68,025 66,398 Minnesota 11,572 12,276 22,918 24,948 Philadelphia 10,386 9,889 20,741 19,871 Southeastern PA 24,343 38,473 50,226 77,712 United Kingdom 3,525 3,965 7,077 7,690 Other 34,444 32,439 69,441 66,834 Segment-level operating revenue 186,547 203,604 376,960 410,556 Reconciliation to total operating revenues Other 107 (86 ) (165 ) (137 ) Total operating revenue $ 186,654 $ 203,518 $ 376,795 $ 410,419 Net operating income Carolinas/Richmond $ 11,219 $ 13,361 $ 22,059 $ 26,208 Chicago/Milwaukee 7,022 6,125 13,815 12,868 Florida 16,741 19,459 34,788 38,561 Houston 8,036 7,689 16,869 14,910 Lehigh/Central PA 24,755 23,647 48,957 46,618 Minnesota 4,850 5,149 9,428 11,134 Philadelphia 7,981 7,310 15,339 14,332 Southeastern PA 14,549 21,426 28,300 42,414 United Kingdom 2,438 2,782 4,842 5,298 Other 22,953 21,516 45,779 44,387 Segment-level net operating income 120,544 128,464 240,176 256,730 Reconciliation to net income Interest expense (30,131 ) (35,066 ) (61,543 ) (69,736 ) Depreciation/amortization expense (1) (39,161 ) (41,772 ) (78,959 ) (85,281 ) Impairment - real estate assets — (1,036 ) — (16,775 ) Gain on property dispositions 3,832 1,249 24,353 3,520 Equity in earnings (loss) of unconsolidated joint ventures 5,583 (5,254 ) 10,497 1,652 General and administrative expense (1) (10,135 ) (9,128 ) (24,927 ) (19,437 ) Income taxes (1) (653 ) (1,051 ) (1,222 ) (1,757 ) Other 1,178 120 1,745 (528 ) Net income $ 51,057 $ 36,526 $ 110,120 $ 68,388 (1) Excludes costs which are included in determining segment-level net operating income. During the six months ended June 30, 2016 , the Company acquired one operating property for a purchase price of $8.0 million . This property, comprising 73,000 square feet of leaseable space, is located in the Company's Chicago/Milwaukee reportable segment. The Company's sales by reportable segment for the three and six months ended June 30, 2016 are as follows: Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Properties Sold Square Feet (000s) Gross Proceeds (000s) Properties Sold Square Feet (000s) Gross Proceeds (000s) Minnesota — — $ — 1 92 $ 9,200 Florida — — — 6 574 111,828 (1 ) Other 1 198 12,000 2 381 22,100 Total 1 198 $ 12,000 9 1,047 $ 143,128 (1) Includes gross proceeds from the sale of 3.5 acres of land. One property totaling 80,000 square feet in the Company's reportable segment classified as "other" was considered held for sale as of June 30, 2016. The Company's total assets by reportable segment as of June 30, 2016 and December 31, 2015 is as follows (in thousands): June 30, 2016 December 31, 2015 Carolinas/Richmond $ 486,825 $ 467,098 Chicago/Milwaukee 438,453 429,390 Florida 788,874 874,352 Houston 527,209 522,285 Lehigh/Central PA 1,243,814 1,157,468 Minnesota 343,473 346,840 Philadelphia 492,193 444,889 Southeastern PA 442,661 448,523 United Kingdom 184,276 215,850 Other 1,580,483 1,586,481 Segment-level total assets 6,528,261 6,493,176 Corporate Other 56,607 64,453 Total assets $ 6,584,868 $ 6,557,629

Accounting for the Impairment o

Accounting for the Impairment or Disposal of Long-Lived Assets	6 Months Ended
	Jun. 30, 2016
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 and six months ended June 30, 2016. During the three months ended June 30, 2015, the Company recognized $1.0 million in impairments which related to the Company's DC Metro reportable segment. During the six months ended June 30, 2015, the Company recognized $16.8 million in impairments, $13.4 million of which related to the Company's Carolinas/Richmond reportable segment, $2.3 million of which related to the Company's Southeastern Pennsylvania reportable segment and $1.0 million of which related to the Company's DC Metro reportable segment. The properties included in the Carolinas/Richmond reportable segment were subsequently sold. The Company determined these impairments based on third party offer prices and quoted offer prices for comparable transactions which are Level 2 and Level 3 inputs, respectively, according to the fair value hierarchy established in ASC 820. These measurements have occurred throughout the respective periods as circumstances arise, and the resulting estimates of fair value are not necessarily reflective of measurements at the period’s end. The Company has evaluated each of its properties and land held for development and has determined that there were no additional valuation adjustments necessary at June 30, 2016 . 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	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 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 June 30, 2016 was $ 140.6 million .

Limited Partners' Equity of the

Limited Partners' Equity of the Operating Partnership	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 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 June 30, 2016 was $ 140.6 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 June 30, 2016 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 June 30, 2016 based on the closing price of the common shares of the Trust at June 30, 2016 was $ 140.6 million .

Noncontrolling Interest - Opera

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units	6 Months Ended
	Jun. 30, 2016
Temporary Equity [Line Items]
Stockholders' Equity Note Disclosure [Text Block]	Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units As of June 30, 2016 , 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	6 Months Ended
	Jun. 30, 2016
Debt Instrument, Fair Value Disclosure [Abstract]
Disclosure of Fair Value of Financial Instruments	Fair Value of Financial Instruments The following disclosure of estimated fair value was determined by management using available market information and appropriate valuation methodologies. However, considerable judgment is necessary to interpret market data and develop estimated fair value. Accordingly, the following estimates are not necessarily indicative of the amounts the Company could have realized on disposition of the financial instruments at June 30, 2016 and December 31, 2015 . 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 12 - Derivative Instruments. The Company used a discounted cash flow model to determine the estimated fair value of its debt as of June 30, 2016 and December 31, 2015. This is a Level 3 fair value calculation. The inputs used in preparing the discounted cash flow model include actual maturity dates and scheduled cash flows as well as estimates for market value discount rates. The Company updates the discounted cash flow model on a quarterly basis to reflect any changes in the Company's debt holdings and changes to discount rate assumptions. The following summarizes the fair value of the Company's mortgage loans and unsecured notes as of December 31, 2015 and June 30, 2016 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2015 $ 307,908 $ 306,334 $ 2,580,108 $ 2,616,395 As of June 30, 2016 $ 284,892 $ 300,180 $ 2,581,663 $ 2,733,980

Unconsolidated Joint Ventures

Unconsolidated Joint Ventures	6 Months Ended
	Jun. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Unconsolidated Joint Ventures Liberty Washington, LP During the six months ended June 30, 2016, Liberty Washington LP (a joint venture in which the Company holds a 25% interest) sold three properties located in Northern Virginia containing 601,000 square feet for $80.5 million . In addition, due to adverse conditions in the Northern Virginia office market, the fair value of two properties owned by the joint venture containing 248,000 square feet were determined to be less than the debt encumbering the properties. As a result, during the three months ended June 30, 2016, the joint venture entered into an arrangement with the mortgage lender to allow a transfer of the two properties to the lender by way of an uncontested trustee sale in satisfaction of nonrecourse mortgage debt totaling $46.4 million . The book values of these properties were written down to fair value in a prior period. During the six months ended June 30, 2016, due to market conditions similar to those discussed above, six properties (including the two properties discussed above) containing 698,000 square feet were transferred to mortgage lenders in satisfaction of an aggregate of $112.5 million in nonrecourse mortgage loans that were secured by the properties. The book values of these properties were written down to fair value in prior periods. The Company's share of gain from property dispositions and extinguishment of debt is included in equity in earnings (loss) of unconsolidated joint ventures in the accompanying consolidated statements of comprehensive income. During the three and six months ended June 30, 2016 the Company's share of gain from extinguishment of debt was $3.3 million and $4.2 million , respectively, and its share of gain on property dispositions was $158,000 and $2.0 million , respectively. Because these loans were nonrecourse, the Company believes that the transfers described above will not have an ongoing effect on its operating results or financial condition.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2016
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 $100.2 million and $101.4 million at June 30, 2016 and December 31, 2015 , 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 and six months ended June 30, 2016 and 2015 (in thousands): Three Months Ended Six Months Ended June 30, 2016 June 30, 2015 June 30, 2016 June 30, 2015 Amount of (loss) gain related to the effective portion recognized in other comprehensive loss $ (700 ) $ 277 $ (2,343 ) $ (1,022 ) Amount of loss related to the effective portion subsequently reclassified to interest expense $ (276 ) $ (351 ) $ (559 ) $ (703 ) Amount of loss related to the ineffective portion recognized in interest expense $ (22 ) $ (2 ) $ (78 ) $ (62 ) The fair value of the Swaps in the amounts of $8.1 million and $7.1 million as of June 30, 2016 and December 31, 2015 , respectively, is included in other liabilities in the accompanying consolidated balance sheets. The Company estimates that $1.0 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 $8.2 million as of June 30, 2016 .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental Matters Substantially all of the Company's properties and land were subject to Phase I Environmental Assessments and when appropriate Phase II Environmental Assessments (collectively, the “Environmental Assessments”) obtained in contemplation of their acquisition by the Company or obtained by predecessor owners prior to the sale of the property or land to the Company. The Environmental Assessments did not reveal, nor is the Company aware of, any non-compliance with environmental laws, environmental liability or other environmental claim that the Company believes would likely have a material adverse effect on the Company. Operating Ground Lease Agreements Future minimum rental payments under the terms of all non-cancelable operating ground leases under which the Company is the lessee, as of June 30, 2016 , were as follows (in thousands): Year Amount 2016 $ 475 2017 950 2018 950 2019 950 2020 950 2021 and thereafter 5,581 Total $ 9,856 Operating ground lease expense for the three and six months ended June 30, 2016 was $237,000 and $493,000 , respectively, as compared to $156,000 and $312,000 , respectively, for the same periods in 2015 . Legal Matters From time to time, the Company is a party to a variety of legal proceedings, claims and assessments arising in the normal course of business. As of June 30, 2016 there were no legal proceedings, claims or assessments that the Company expects to have a material adverse effect on the Company’s business or financial statements. Other As of June 30, 2016 , the Company had letter of credit obligations of $10.2 million . The Company believes that the likelihood is remote that there will be a draw upon these letter of credit obligations. As of June 30, 2016 , the Company had 25 buildings under development. These buildings are expected to contain, when completed, a total of 7.0 million square feet of leasable space and represent an anticipated aggregate investment of $642.7 million . At June 30, 2016 , development in progress totaled $438.5 million . In addition, as of June 30, 2016 , the Company had invested $11.4 million in deferred leasing costs related to these development buildings. Also, as of June 30, 2016 , the Company had signed an agreement, subject to the satisfaction of certain conditions, to develop an office building with a cost of approximately $100 million on land to be owned by the future occupant of the building and with funds to be advanced by the future occupant, and to guarantee the timely lien-free completion of construction of the building and the payment, subject to certain exceptions, of any cost overruns in the development of the building, all in consideration for a development fee payable to the Company. As of June 30, 2016 , the Company was committed to $48.5 million in improvements on certain buildings and land parcels. As of June 30, 2016 , the Company was committed to $28.7 million in future land purchases. As of June 30, 2016 , the Company was obligated to pay for tenant improvements not yet completed for a maximum of $31.2 million . As of June 30, 2016 , the Company was committed to fund up to $4 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 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 four buildings for its unconsolidated joint ventures which represent an anticipated aggregate investment by the joint ventures of $1.0 billion . The Company maintains cash and cash equivalents at financial institutions. The combined account balances at each institution typically exceed FDIC insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. The Company believes the risk is not significant.

Supplemental Disclosure to Stat

Supplemental Disclosure to Statements of Cash Flows	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016 and 2015 (amounts in thousands): 2016 2015 Write-off of fully depreciated/amortized property and deferred costs $ 19,002 $ 28,877 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 33,857 $ 76,533 Unrealized loss on cash flow hedge $ (1,795 ) $ (319 ) Changes in accrued development capital expenditures $ 2,383 $ (10,974 ) Capitalized equity-based compensation in development in progress $ 808 $ — Amounts paid in cash for deferred leasing costs incurred in connection with signed leases with tenants are paid in conjunction with improving (acquiring) property, plant and equipment. Such costs are not contained within net real estate. However, they are integral to the completion of a tenant lease and ultimately are related to the improvement and thus the value of the Company’s property, plant and equipment. They are therefore included in investing activities in the Company’s consolidated statements of cash flows.

Subsequent Events (Notes)

Subsequent Events (Notes)	6 Months Ended
	Jun. 30, 2016
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events On July 22, 2016 the Company entered into an agreement to sell 108 properties totaling 7.6 million square feet of leasable space and 26.7 acres of land for $969 million .

Organization and Basis of Pre22

Organization and Basis of Presentation (Policy)	6 Months Ended
	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which supersedes nearly all existing revenue recognition guidance. The standard clarifies the required factors that an entity must consider when recognizing revenue. The standard also requires additional disclosures concerning contracts with customers, judgments concerning revenue recognition, and assets recognized for the costs to obtain or fulfill a contract. ASU 2014-09 is effective for the Company beginning January 1, 2018. The Company is evaluating the impact ASU 2014-09 will have on its financial position and results of operations and has not yet selected a transition method. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis (Topic 810) ("ASU 2015-02"). The standard requires that all entities re-evaluate and revise consolidation documentation for limited partnerships and similar legal entities. It makes changes to both the variable interest model and voting model. The Company adopted ASU 2015-02 beginning January 1, 2016. The adoption of ASU 2015-02 did not have a material impact on the Company's financial position and results of operations. 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. 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. Early adoption of ASU 2016-05 is permitted. The standard allows application on a prospective or modified retrospective basis. The Company does not believe that ASU 2016-05 will have a material impact on its financial position and results of operations. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting ("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. ASU 2016-09 is effective for the Company beginning January 1, 2017. Early adoption of ASU 2016-09 is permitted. Certain amendments in the standard are to be applied retrospectively and certain amendments are to be applied prospectively. The Company is evaluating the impact ASU 2016-09 will have on its financial position and results of operations.

Income per Common Share of th23

Income per Common Share of the Trust (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted income per common share of the Trust (in thousands except per share amounts): For the Three Months Ended For the Three Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 49,627 145,995 $ 0.34 $ 35,513 148,778 $ 0.24 Dilutive shares for long-term compensation plans — 740 — 676 Net income available to common shareholders - diluted $ 49,627 146,735 $ 0.34 $ 35,513 149,454 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 107,181 146,002 $ 0.73 $ 66,464 148,574 $ 0.45 Dilutive shares for long-term compensation plans — 620 — 673 Net income available to common shareholders - diluted $ 107,181 146,622 $ 0.73 $ 66,464 149,247 $ 0.45

Income per Common Unit of the24

Income per Common Unit of the Operating Partnership (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 49,627 145,995 $ 0.34 $ 35,513 148,778 $ 0.24 Dilutive shares for long-term compensation plans — 740 — 676 Net income available to common shareholders - diluted $ 49,627 146,735 $ 0.34 $ 35,513 149,454 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Shares (Denominator) Per Share Income (Numerator) Weighted Average Shares (Denominator) Per Share Net income available to common shareholders - basic $ 107,181 146,002 $ 0.73 $ 66,464 148,574 $ 0.45 Dilutive shares for long-term compensation plans — 620 — 673 Net income available to common shareholders - diluted $ 107,181 146,622 $ 0.73 $ 66,464 149,247 $ 0.45
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 June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 50,944 $ 36,471 Less: Preferred unit distributions (118 ) (118 ) Income available to common unitholders - basic $ 50,826 149,534 $ 0.34 $ 36,353 152,317 $ 0.24 Dilutive units for long-term compensation plans — 740 — 676 Income available to common unitholders - diluted $ 50,826 150,274 $ 0.34 $ 36,353 152,993 $ 0.24 For the Six Months Ended For the Six Months Ended June 30, 2016 June 30, 2015 Income (Numerator) Weighted Average Units (Denominator) Per Unit Income (Numerator) Weighted Average Units (Denominator) Per Unit Income - net of noncontrolling interest - consolidated joint ventures $ 110,007 $ 68,275 Less: Preferred unit distributions (236 ) (236 ) Income available to common unitholders - basic 109,771 149,541 $ 0.73 68,039 152,114 $ 0.45 Dilutive units for long-term compensation plans — 620 — 673 Income available to common unitholders - diluted $ 109,771 150,161 $ 0.73 $ 68,039 152,787 $ 0.45

Accumulated Other Comprehensi25

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016 2015 Foreign Currency Translation: Beginning balance $ (17,256 ) $ (5,823 ) Translation adjustment (18,596 ) 1,741 Ending balance (35,852 ) (4,082 ) Derivative Instruments: Beginning balance (865 ) (377 ) Unrealized loss (2,354 ) (1,022 ) Reclassification adjustment (1) 559 703 Ending balance (2,660 ) (696 ) Total accumulated other comprehensive loss (38,512 ) (4,778 ) Less: portion included in noncontrolling interest – operating partnership 709 (85 ) Total accumulated other comprehensive loss included in shareholders' equity/owners' equity $ (37,803 ) $ (4,863 ) (1) Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2016
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 Six Months Ended June 30, Ended June 30, 2016 2015 2016 2015 Operating revenue Carolinas/Richmond $ 16,174 $ 20,212 $ 31,934 $ 40,547 Chicago/Milwaukee 10,319 8,931 20,512 18,724 Florida 27,798 31,424 57,115 62,358 Houston 14,204 13,151 28,971 25,474 Lehigh/Central PA 33,782 32,844 68,025 66,398 Minnesota 11,572 12,276 22,918 24,948 Philadelphia 10,386 9,889 20,741 19,871 Southeastern PA 24,343 38,473 50,226 77,712 United Kingdom 3,525 3,965 7,077 7,690 Other 34,444 32,439 69,441 66,834 Segment-level operating revenue 186,547 203,604 376,960 410,556 Reconciliation to total operating revenues Other 107 (86 ) (165 ) (137 ) Total operating revenue $ 186,654 $ 203,518 $ 376,795 $ 410,419 Net operating income Carolinas/Richmond $ 11,219 $ 13,361 $ 22,059 $ 26,208 Chicago/Milwaukee 7,022 6,125 13,815 12,868 Florida 16,741 19,459 34,788 38,561 Houston 8,036 7,689 16,869 14,910 Lehigh/Central PA 24,755 23,647 48,957 46,618 Minnesota 4,850 5,149 9,428 11,134 Philadelphia 7,981 7,310 15,339 14,332 Southeastern PA 14,549 21,426 28,300 42,414 United Kingdom 2,438 2,782 4,842 5,298 Other 22,953 21,516 45,779 44,387 Segment-level net operating income 120,544 128,464 240,176 256,730 Reconciliation to net income Interest expense (30,131 ) (35,066 ) (61,543 ) (69,736 ) Depreciation/amortization expense (1) (39,161 ) (41,772 ) (78,959 ) (85,281 ) Impairment - real estate assets — (1,036 ) — (16,775 ) Gain on property dispositions 3,832 1,249 24,353 3,520 Equity in earnings (loss) of unconsolidated joint ventures 5,583 (5,254 ) 10,497 1,652 General and administrative expense (1) (10,135 ) (9,128 ) (24,927 ) (19,437 ) Income taxes (1) (653 ) (1,051 ) (1,222 ) (1,757 ) Other 1,178 120 1,745 (528 ) Net income $ 51,057 $ 36,526 $ 110,120 $ 68,388 (1) Excludes costs which are included in determining segment-level net operating income.
Real Estate Properties Sold [Table Text Block]	The Company's sales by reportable segment for the three and six months ended June 30, 2016 are as follows: Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Properties Sold Square Feet (000s) Gross Proceeds (000s) Properties Sold Square Feet (000s) Gross Proceeds (000s) Minnesota — — $ — 1 92 $ 9,200 Florida — — — 6 574 111,828 (1 ) Other 1 198 12,000 2 381 22,100 Total 1 198 $ 12,000 9 1,047 $ 143,128 (1) Includes gross proceeds from the sale of 3.5 acres of land.
Assets by Segment and Reconciliation to Consolidated[Table Text Block]	The Company's total assets by reportable segment as of June 30, 2016 and December 31, 2015 is as follows (in thousands): June 30, 2016 December 31, 2015 Carolinas/Richmond $ 486,825 $ 467,098 Chicago/Milwaukee 438,453 429,390 Florida 788,874 874,352 Houston 527,209 522,285 Lehigh/Central PA 1,243,814 1,157,468 Minnesota 343,473 346,840 Philadelphia 492,193 444,889 Southeastern PA 442,661 448,523 United Kingdom 184,276 215,850 Other 1,580,483 1,586,481 Segment-level total assets 6,528,261 6,493,176 Corporate Other 56,607 64,453 Total assets $ 6,584,868 $ 6,557,629

Noncontrolling Interest - Ope27

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Tables)	6 Months Ended
	Jun. 30, 2016
Temporary Equity [Line Items]
Schedule of Temporary Equity [Table Text Block]	As of June 30, 2016 , 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 F28

Disclosure of Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
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, 2015 and June 30, 2016 (in thousands): Mortgage Loans Unsecured Notes Carrying Value Fair Value Carrying Value Fair Value As of December 31, 2015 $ 307,908 $ 306,334 $ 2,580,108 $ 2,616,395 As of June 30, 2016 $ 284,892 $ 300,180 $ 2,581,663 $ 2,733,980

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table presents the location in the financial statements of the gains or losses recognized related to the Company’s cash flow hedges for the three and six months ended June 30, 2016 and 2015 (in thousands): Three Months Ended Six Months Ended June 30, 2016 June 30, 2015 June 30, 2016 June 30, 2015 Amount of (loss) gain related to the effective portion recognized in other comprehensive loss $ (700 ) $ 277 $ (2,343 ) $ (1,022 ) Amount of loss related to the effective portion subsequently reclassified to interest expense $ (276 ) $ (351 ) $ (559 ) $ (703 ) Amount of loss related to the ineffective portion recognized in interest expense $ (22 ) $ (2 ) $ (78 ) $ (62 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rental Payments	Future minimum rental payments under the terms of all non-cancelable operating ground leases under which the Company is the lessee, as of June 30, 2016 , were as follows (in thousands): Year Amount 2016 $ 475 2017 950 2018 950 2019 950 2020 950 2021 and thereafter 5,581 Total $ 9,856

Supplemental Disclosure to St31

Supplemental Disclosure to Statements of Cash Flows (Tables)	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016 and 2015 (amounts in thousands): 2016 2015 Write-off of fully depreciated/amortized property and deferred costs $ 19,002 $ 28,877 Write-off of depreciated/amortized property and deferred costs due to sale/demolition $ 33,857 $ 76,533 Unrealized loss on cash flow hedge $ (1,795 ) $ (319 ) Changes in accrued development capital expenditures $ 2,383 $ (10,974 ) Capitalized equity-based compensation in development in progress $ 808 $ —

Organization and Basis of Pre32

Organization and Basis of Presentation (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Ownership interest in operating partnership - Limited Partnership	97.60%
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	$ 19.8	$ 20.5
Maximum exposure to loss	$ 19.8	$ 20.5

Income per Common Share of th33

Income per Common Share of the Trust (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income (Numerator) [Abstract]
Net income available to common shareholders	$ 49,627	$ 35,513	$ 107,181	$ 66,464
Weighted Average Shares (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	145,995	148,778	146,002	148,574
Dilutive shares for long-term compensation plans	740	676	620	673
Weighted Average Number of Shares Outstanding, Diluted	146,735	149,454	146,622	149,247
Common shares [Member]
Earnings Per Share, Basic [Abstract]
Income per common share - basic	$ 0.34	$ 0.24	$ 0.73	$ 0.45
Earnings Per Share, Diluted [Abstract]
Income per common share - diluted	$ 0.34	$ 0.24	$ 0.73	$ 0.45

Income per Common Share of th34

Income per Common Share of the Trust Income per Common Share of the Trust - Anti-dilutive Options (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stock Option [Member]
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	885,000	1,528,000	1,668,000	1,448,000

Income per Common Share of th35

Income per Common Share of the Trust - Options Exercised (Details) - shares	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Stock Option [Member] | Common shares [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	97,000	112,000	65,000

Income per Common Share of th36

Income per Common Share of the Trust - Share Repurchase (Details) - Common shares [Member] - 2015 Share Repurchase Program [Member] - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016
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	0	1.4
Amount paid for repurchase of shares		$ 40.9
Stock Acquired, Average Cost Per Share		$ 29.28

Income per Common Unit of the37

Income per Common Unit of the Operating Partnership - Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income (Numerator) [Abstract]
Net income available to common shareholders	$ 49,627	$ 35,513	$ 107,181	$ 66,464
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	145,995	148,778	146,002	148,574
Dilutive units for long-term compensation plans	740	676	620	673
Weighted Average Number of Shares Outstanding, Diluted	146,735	149,454	146,622	149,247
Liberty Property Limited Partnership [Member]
Income (Numerator) [Abstract]
Income from continuing operations net of noncontrolling interest - consolidated joint ventures	$ 50,944	$ 36,471	$ 110,007	$ 68,275
Less: Preferred unit distributions	(118)	(118)	(236)	(236)
Net income available to common shareholders	$ 50,826	$ 36,353	$ 109,771	$ 68,039
Weighted Average Units (Denominator) [Abstract]
Weighted Average Number of Shares Outstanding, Basic	149,534	152,317	149,541	152,114
Dilutive units for long-term compensation plans	740	676	620	673
Weighted Average Number of Shares Outstanding, Diluted	150,274	152,993	150,161	152,787
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Unit, Basic [Abstract]
Income per common share - basic	$ 0.34	$ 0.24	$ 0.73	$ 0.45
Earnings Per Unit, Diluted [Abstract]
Income per common share - diluted	$ 0.34	$ 0.24	$ 0.73	$ 0.45

Income per Common Unit of the38

Income per Common Unit of the Operating Partnership - Anti-dilutive Options (Details) - Stock Option [Member] - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Options Excluded from Computation of Earnings Per Share	885,000	1,528,000	1,668,000	1,448,000
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	885,000	1,528,000	1,668,000	1,448,000

Income per Common Unit of the39

Income per Common Unit of the Operations Partnership - Options Exercised (Details) - shares	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Liberty Property Limited Partnership [Member] | Stock Option [Member] | Common Units [Member]
Stock Option Exercises [Line Items]
Amount of Options Exercises in Period	97,000	112,000	65,000

Income per Common Unit of the40

Income per Common Unit of the Operating Partnership - Unit Repurchase (Details) - 2015 Share Repurchase Program [Member] - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016
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	0	1.4
Amount paid for repurchase of units		$ 40.9
Stock Acquired, Average Cost Per Share		$ 29.28
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	0	1.4
Amount paid for repurchase of units		$ 40.9
Liberty Property Limited Partnership [Member] | Common shares [Member]
Class of Stock [Line Items]
Stock Acquired, Average Cost Per Share		$ 29.28

Accumulated Other Comprehensi41

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 3,009,947
Ending Balance		2,932,447
Total accumulated other comprehensive loss		3,009,947		$ 2,932,447	$ 3,009,947
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				2,876,817	2,952,928
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		(17,256)	$ (5,823)
Unrealized loss		(18,596)	1,741
Ending Balance		(35,852)	(4,082)
Total accumulated other comprehensive loss		(17,256)	(5,823)	(35,852)	(17,256)	$ (4,082)
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		(865)	(377)
Unrealized loss		(2,354)	(1,022)
Reclassification adjustment	[1]	559	703
Ending Balance		(2,660)	(696)
Total accumulated other comprehensive loss		(865)	(377)	(2,660)	(865)	(696)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		(38,512)	(4,778)
Total accumulated other comprehensive loss		(38,512)	(4,778)	(38,512)		(4,778)
AOCI Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		709	(85)
Total accumulated other comprehensive loss		709	$ (85)	709		(85)
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(17,893)
Ending Balance		(37,803)
Total accumulated other comprehensive loss		$ (17,893)		(37,803)	$ (17,893)
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				$ (37,803)		$ (4,863)
[1]	Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.

Performance of the Reportable S

Performance of the Reportable Segments Based on Property Level Operating Income (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Operating revenue		$ 186,654,000	$ 203,518,000	$ 376,795,000	$ 410,419,000
Net operating income		67,533,000	70,185,000	128,776,000	122,014,000
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense		(30,131,000)	(35,066,000)	(61,543,000)	(69,736,000)
Depreciation and amortization expense				(109,047,000)	(117,160,000)
Impairment - real estate assets		0	(1,036,000)	0	(16,775,000)
Gain on property dispositions		3,832,000	1,249,000	24,353,000	3,520,000
Equity in earnings (loss) of unconsolidated joint ventures		5,583,000	(5,254,000)	10,497,000	1,652,000
General and administrative expense		(15,629,000)	(17,053,000)	(36,619,000)	(35,855,000)
Income taxes		(752,000)	(1,169,000)	(1,553,000)	(2,014,000)
Net income		51,057,000	36,526,000	110,120,000	68,388,000
Carolinas Richmond [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Impairment - real estate assets					(13,400,000)
Southeastern PA [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Impairment - real estate assets					(2,300,000)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenue		0	0	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenue		186,547,000	203,604,000	376,960,000	410,556,000
Net operating income		120,544,000	128,464,000	240,176,000	256,730,000
Operating Segments [Member] | Carolinas Richmond [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		16,174,000	20,212,000	31,934,000	40,547,000
Net operating income		11,219,000	13,361,000	22,059,000	26,208,000
Operating Segments [Member] | Chicago Milwaukee [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		10,319,000	8,931,000	20,512,000	18,724,000
Net operating income		7,022,000	6,125,000	13,815,000	12,868,000
Operating Segments [Member] | Florida [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		27,798,000	31,424,000	57,115,000	62,358,000
Net operating income		16,741,000	19,459,000	34,788,000	38,561,000
Operating Segments [Member] | Houston [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		14,204,000	13,151,000	28,971,000	25,474,000
Net operating income		8,036,000	7,689,000	16,869,000	14,910,000
Operating Segments [Member] | Lehigh Central PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		33,782,000	32,844,000	68,025,000	66,398,000
Net operating income		24,755,000	23,647,000	48,957,000	46,618,000
Operating Segments [Member] | Minnesota [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		11,572,000	12,276,000	22,918,000	24,948,000
Net operating income		4,850,000	5,149,000	9,428,000	11,134,000
Operating Segments [Member] | Philadelphia [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		10,386,000	9,889,000	20,741,000	19,871,000
Net operating income		7,981,000	7,310,000	15,339,000	14,332,000
Operating Segments [Member] | Southeastern PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		24,343,000	38,473,000	50,226,000	77,712,000
Net operating income		14,549,000	21,426,000	28,300,000	42,414,000
Operating Segments [Member] | United Kingdom [Member] | UNITED KINGDOM
Segment Reporting Information [Line Items]
Operating revenue		3,525,000	3,965,000	7,077,000	7,690,000
Net operating income		2,438,000	2,782,000	4,842,000	5,298,000
Operating Segments [Member] | Other Segments [Member] | North America [Member]
Segment Reporting Information [Line Items]
Operating revenue		34,444,000	32,439,000	69,441,000	66,834,000
Net operating income		22,953,000	21,516,000	45,779,000	44,387,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenue		107,000	(86,000)	(165,000)	(137,000)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense		(30,131,000)	(35,066,000)	(61,543,000)	(69,736,000)
Depreciation and amortization expense	[1]	(39,161,000)	(41,772,000)	(78,959,000)	(85,281,000)
Impairment - real estate assets		0	(1,036,000)	0	(16,775,000)
Gain on property dispositions		3,832,000	1,249,000	24,353,000	3,520,000
Equity in earnings (loss) of unconsolidated joint ventures		5,583,000	(5,254,000)	10,497,000	1,652,000
General and administrative expense	[1]	(10,135,000)	(9,128,000)	(24,927,000)	(19,437,000)
Income taxes	[1]	(653,000)	(1,051,000)	(1,222,000)	(1,757,000)
Other		$ 1,178,000	$ 120,000	$ 1,745,000	$ (528,000)
[1]	Excludes costs which are included in determining segment-level net operating income.

Segment Information Building Ac

Segment Information Building Acquisitions and Dispositions (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016USD ($)ft²abldg	Jun. 30, 2016USD ($)ft²abldg	Jun. 30, 2015USD ($)
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Real Estate Held-for-investment | $		$ 139,814	$ 156,891
Operating Segments [Member] | 2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	9	9
Net Rentable Area | ft²	1,047,000	1,047,000
Proceeds from Sale of Real Estate Held-for-investment | $		$ 143,128
Operating Segments [Member] | 2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Minnesota [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1	1
Net Rentable Area | ft²	92,000	92,000
Proceeds from Sale of Real Estate Held-for-investment | $		$ 9,200
Operating Segments [Member] | 2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Florida [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	6	6
Net Rentable Area | ft²	574,000	574,000
Proceeds from Sale of Real Estate Held-for-investment | $		$ 111,828
Operating Segments [Member] | 2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Florida [Member] | Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Area of Land | a	3.5	3.5
Operating Segments [Member] | 2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Other Segments [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	2	2
Net Rentable Area | ft²	381,000	381,000
Proceeds from Sale of Real Estate Held-for-investment | $		$ 22,100
Operating Segments [Member] | 2016 sales current [Member] | Disposal Group, Not Discontinued Operations [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1	1
Net Rentable Area | ft²	198,000	198,000
Proceeds from Sale of Real Estate Held-for-investment | $	$ 12,000
Operating Segments [Member] | 2016 sales current [Member] | Disposal Group, Not Discontinued Operations [Member] | Minnesota [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	0	0
Net Rentable Area | ft²	0	0
Proceeds from Sale of Real Estate Held-for-investment | $	$ 0
Operating Segments [Member] | 2016 sales current [Member] | Disposal Group, Not Discontinued Operations [Member] | Florida [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	0	0
Net Rentable Area | ft²	0	0
Proceeds from Sale of Real Estate Held-for-investment | $	$ 0
Operating Segments [Member] | 2016 sales current [Member] | Disposal Group, Not Discontinued Operations [Member] | Other Segments [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1	1
Net Rentable Area | ft²	198,000	198,000
Proceeds from Sale of Real Estate Held-for-investment | $	$ 12,000
Operating Segments [Member] | 2016 sales current [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Other Segments [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1	1
Net Rentable Area | ft²	80,000	80,000
2016 acquisitions [Member] | Operating Segments [Member] | Chicago Milwaukee [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Number of Real Estate Properties | bldg	1	1
Net Rentable Area | ft²	73,000	73,000
Payments to Acquire Commercial Real Estate | $		$ 8,000

Segment Information Total Asset

Segment Information Total Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Assets	$ 6,584,868	$ 6,557,629
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	6,528,261	6,493,176
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	56,607	64,453
North America [Member] | Operating Segments [Member] | Carolinas Richmond [Member]
Segment Reporting Information [Line Items]
Assets	486,825	467,098
North America [Member] | Operating Segments [Member] | Chicago Milwaukee [Member]
Segment Reporting Information [Line Items]
Assets	438,453	429,390
North America [Member] | Operating Segments [Member] | Florida [Member]
Segment Reporting Information [Line Items]
Assets	788,874	874,352
North America [Member] | Operating Segments [Member] | Houston [Member]
Segment Reporting Information [Line Items]
Assets	527,209	522,285
North America [Member] | Operating Segments [Member] | Lehigh Central PA [Member]
Segment Reporting Information [Line Items]
Assets	1,243,814	1,157,468
North America [Member] | Operating Segments [Member] | Minnesota [Member]
Segment Reporting Information [Line Items]
Assets	343,473	346,840
North America [Member] | Operating Segments [Member] | Philadelphia [Member]
Segment Reporting Information [Line Items]
Assets	492,193	444,889
North America [Member] | Operating Segments [Member] | Southeastern PA [Member]
Segment Reporting Information [Line Items]
Assets	442,661	448,523
North America [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	1,580,483	1,586,481
UNITED KINGDOM | Operating Segments [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Assets	$ 184,276	$ 215,850

Accounting for the Impairment45

Accounting for the Impairment or Disposal of Long-Lived Assets Asset Impairment (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Property, Plant and Equipment [Line Items]
Impairment - real estate assets	$ 0	$ 1,036,000	$ 0	$ 16,775,000
Carolinas Richmond [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets				13,400,000
Southeastern PA [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets				2,300,000
DC Metro [Member]
Property, Plant and Equipment [Line Items]
Impairment - real estate assets		$ 1,000,000		$ 1,000,000

Noncontrolling Interests of t46

Noncontrolling Interests of the Trust- Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Redeemable Noncontrolling Interest [Line Items]
Limited Partners' common units outstanding	3,539,075	3,539,075
Market value of common units based on closing price	$ 140.6
Liberty Property Limited Partnership [Member]
Redeemable Noncontrolling Interest [Line Items]
Limited Partners' common units outstanding	3,539,075	3,539,075

Limited Partners' Equity of t47

Limited Partners' Equity of the Operating Partnership - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Limited Partners' Capital Account [Line Items]
Limited Partners' common units outstanding	3,539,075	3,539,075
Liberty Property Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Limited Partners' common units outstanding	3,539,075	3,539,075
market value of the outstanding common units	$ 140.6

Noncontrolling Interest - Ope48

Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Temporary Equity [Line Items]
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2016 and December 31, 2015	$ 7,537	$ 7,537
Series I 2 [Member]
Temporary Equity [Line Items]
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of June 30, 2016 and December 31, 2015	$ 7,537
Units	301,483	301,483
Liquidation Preference	$ 25
Dividend Rate	6.25%

Disclosure of Fair Value of F49

Disclosure of Fair Value of Financial Instruments (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Estimate of Fair Value Measurement [Member] | Mortgage Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 300,180	$ 306,334
Estimate of Fair Value Measurement [Member] | Unsecured Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	2,733,980	2,616,395
Portion at Other than Fair Value Measurement [Member] | Mortgage Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	284,892	307,908
Portion at Other than Fair Value Measurement [Member] | Unsecured Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 2,581,663	$ 2,580,108

Unconsolidated Joint Ventures (

Unconsolidated Joint Ventures (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2016USD ($)ft²bldg	Jun. 30, 2016USD ($)ft²bldg	Jun. 30, 2015USD ($)
Liberty Washington LP [Abstract]
Gain on sale of properties		$ 24,353,000	$ 3,520,000
Liberty Washington, LP [Member]
Liberty Washington LP [Abstract]
Equity Method Investment, Ownership Percentage	25.00%	25.00%
Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Joint venture, 2016 sales [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Net Rentable Area | ft²	601,000	601,000
Number of Real Estate Properties | bldg	3	3
Proceeds from Sale of Property		$ 80,500,000
Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Joint venture, 2016 foreclosure transfer [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Net Rentable Area | ft²	248,000	248,000
Number of Real Estate Properties | bldg	2	2
Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Joint venture, 2016 transfer to lender [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Net Rentable Area | ft²	698,000	698,000
Number of Real Estate Properties | bldg	6	6
Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Mortgages [Member] | Joint venture, 2016 foreclosure transfer [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Extinguishment of Debt, Amount	$ 46,400,000
Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Mortgages [Member] | Joint venture, 2016 transfer to lender [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Extinguishment of Debt, Amount		$ 112,500,000
General Partner [Member] | Gain on equity method investments [Member] | Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Joint venture, 2016 foreclosure transfer [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Gain on sale of properties	158,000
General Partner [Member] | Gain on equity method investments [Member] | Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Joint venture, 2016 transfer to lender [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Gain on sale of properties		2,000,000
General Partner [Member] | Gain on equity method investments [Member] | Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Mortgages [Member] | Joint venture, 2016 foreclosure transfer [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Gain on extinguishment of debt	$ 3,300,000
General Partner [Member] | Gain on equity method investments [Member] | Liberty Washington, LP [Member] | Disposal Group, Not Discontinued Operations [Member] | Mortgages [Member] | Joint venture, 2016 transfer to lender [Member] | Building and Building Improvements [Member]
Liberty Washington LP [Abstract]
Gain on extinguishment of debt		$ 4,200,000

Derivative Instruments (Details

Derivative Instruments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Interest Rate Derivatives [Abstract]
Number of interest rate swap contracts	3		3
aggregate notional amount	$ 100,200		$ 100,200		$ 101,400
Termination value of interest rate swap, including accrued interest	8,200		8,200
Interest Rate Cash Flow Hedges [Abstract]
Fair value of interest rate swaps	8,100		8,100		$ 7,100
Amount estimated to be reclassified from accumulated other comprehensive income as an increase to interest expense	1,000		1,000
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 (loss) gain related to the effective portion recognized in other comprehensive loss	(700)	$ 277	(2,343)	$ (1,022)
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	(276)	(351)	(559)	(703)
Amount of loss related to the ineffective portion recognized in interest expense	$ (22)	$ (2)	$ (78)	$ (62)

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Rental Payments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
2,016	$ 475,000		$ 475,000
2,017	950,000		950,000
2,018	950,000		950,000
2,019	950,000		950,000
2,020	950,000		950,000
2021 and thereafter	5,581,000		5,581,000
Total	9,856,000		9,856,000
Other Expenses [Abstract]
Operating ground lease expense	$ 237,000	$ 156,000	$ 493,000	$ 312,000

Commitments and Contingencies53

Commitments and Contingencies - Loss Contingencies (Details) $ in Millions	Jun. 30, 2016USD ($)
Legal Matters [Abstract]
Loss Contingency, Pending Claims, Number	0
Other [Abstract]
Letter of credit obligations	$ 10.2
Contractual Obligation	$ 4

Commitments and Contingencies54

Commitments and Contingencies - Supply Commitments (Details) $ in Thousands, ft² in Millions	Jun. 30, 2016USD ($)ft²bldgproperties	Dec. 31, 2015USD ($)
Supply Commitment [Line Items]
Development in Process	$ 438,542	$ 360,948
Development not owned [Member] | Construction in Progress [Member]
Supply Commitment [Line Items]
Total anticipated development cost	$ 100,000
Construction in Progress [Member]
Supply Commitment [Line Items]
Net Rentable Area | ft²	7
Number of Real Estate Properties | properties	25
Total anticipated development cost	$ 642,700
Deferred leasing costs in development	11,400
Buildings and land parcels [Member]
Supply Commitment [Line Items]
Remaining amount committed or obligated to pay for the benefit of current or future tenants	48,500
Tenant Improvements [Member]
Supply Commitment [Line Items]
Tenant improvements not yet completed	$ 31,200
Equity Method Investments [Member] | Construction in Progress [Member] | Construction in Progress [Member]
Supply Commitment [Line Items]
Number of Real Estate Properties | bldg	4
Total anticipated development cost	$ 1,000,000

Commitments and Contingencies55

Commitments and Contingencies - Purchase Commitments (Details) $ in Millions	Jun. 30, 2016USD ($)
Land Purchases [Member]
Long-term Purchase Commitment [Line Items]
Remaining amount commitment to future land purchases	$ 28.7

Supplemental Disclosure to St56

Supplemental Disclosure to Statements of Cash Flows (Details) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Write-off of fully depreciated/amortized property and deferred costs	$ 19,002,000	$ 28,877,000
Write-off of depreciated/amortized property and deferred costs due to sale/demolition	33,857,000	76,533,000
Unrealized loss on cash flow hedge	(1,795,000)	(319,000)
Changes in accrued development capital expenditures	2,383,000	(10,974,000)
Capitalized equity-based compensation in development in progress	$ 808,000	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ in Thousands, ft² in Millions	1 Months Ended	6 Months Ended
	Jul. 22, 2016USD ($)ft²abldg	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)
Subsequent Event [Line Items]
Proceeds from Sale of Real Estate Held-for-investment		$ 139,814	$ 156,891
2016 sales [Member] | Disposal Group, Not Discontinued Operations [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Real Estate Properties | bldg	108
Area of Real Estate Property | ft²	7.6
Area of Land | a	26.7
Proceeds from Sale of Real Estate Held-for-investment	$ 969,000