Area of land held.

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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-Publisher FASB
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-Topic 942
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-Subparagraph (SX 210.9-03.15(3),(4))
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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount for notes payable (written promise to pay), due to related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
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-Paragraph 1
-Subparagraph (SX 210.7-03.17)
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-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	credit
Period Type:	instant

- Definition

For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Publisher FASB
-Name Accounting Standards Codification
-Glossary Related Parties
-URI http://asc.fasb.org/extlink&oid=16382449

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Identify the stated interest rate per the agreement, for example, leasing and debt arrangements between related parties.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
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-Subparagraph (SX 210.6-07.1(c))
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Investments in Unconsolidated Joint Ventures - Related Party (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) a ft²	Dec. 31, 2014 USD ($) a ft² bldg	Dec. 31, 2013 USD ($)
Related Party Transaction [Line Items]
Impairment - real estate assets	$ 18,244,000	$ 117,000	$ 248,000
Northern Virginia and Washington DC [Member] \| Liberty Washington, LP [Member]
Related Party Transaction [Line Items]
Impairment - real estate assets		172,700,000
Northern Virginia and Washington DC [Member] \| Liberty Washington, LP [Member] \| Building and Building Improvements [Member]
Related Party Transaction [Line Items]
Leaseable square feet (unaudited) \| ft²	2,300,000
Northern Virginia and Washington DC [Member] \| Liberty Washington, LP [Member] \| Land and Land Improvements [Member]
Related Party Transaction [Line Items]
Acres of developable land (unaudited) \| a	6
Northern Virginia [Member] \| Liberty Washington, LP [Member]
Related Party Transaction [Line Items]
Impairment - real estate assets	$ 56,800,000
Northern Virginia [Member] \| Liberty Washington, LP [Member] \| General Partner [Member] \| Investments in and advances to unconsolidated joint ventures [Member]
Related Party Transaction [Line Items]
Impairment - real estate assets	$ 11,500,000
New Jersey [Member] \| Liberty Venture I, LP [Member]
Related Party Transaction [Line Items]
Leaseable square feet (unaudited) \| ft²	3,700,000
New Jersey [Member] \| Liberty Venture I, LP [Member] \| Building and Building Improvements [Member]
Related Party Transaction [Line Items]
Leaseable square feet (unaudited) \| a	198,000
New Jersey [Member] \| Liberty Venture I, LP [Member] \| Land and Land Improvements [Member]
Related Party Transaction [Line Items]
Acres of developable land (unaudited) \| a	36
United Kingdom [Member] \| Kings Hill Unit Trust [Member] \| General Partner [Member] \| Investments in and advances to unconsolidated joint ventures [Member]
Related Party Transaction [Line Items]
Impairment - real estate assets			800,000
United Kingdom [Member] \| Kings Hill Unit Trust [Member] \| Building and Building Improvements [Member]
Related Party Transaction [Line Items]
Leaseable square feet (unaudited) \| ft²	490,000
Purchase from liberty property limited partnership [Member] \| New Jersey [Member] \| Liberty Venture I, LP [Member] \| Building and Building Improvements [Member] \| General Partner [Member] \| 2015 acquisitions [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties		2,500,000
Related Party Transaction, Purchases from Related Party		$ 43,000,000
Number of buildings \| bldg		3
Leaseable square feet (unaudited) \| ft²		603,000
Purchase from liberty property limited partnership [Member] \| New Jersey [Member] \| Liberty Venture I, LP [Member] \| Land and Land Improvements [Member] \| General Partner [Member] \| 2015 acquisitions [Member]
Related Party Transaction [Line Items]
Acres of developable land (unaudited) \| a		51
Liberty Venture I, LP [Member] \| New Jersey [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue	$ 1,600,000	$ 1,400,000	578,000
Liberty Venture I, LP [Member] \| New Jersey [Member] \| Equity Method Investee [Member] \| Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Due from Related Parties	451,000
Kings Hill Unit Trust [Member] \| United Kingdom [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue	$ 304,000	285,000	237,000
Related Party Transaction, Rate	10.00%
Kings Hill Unit Trust [Member] \| United Kingdom [Member] \| Equity Method Investee [Member] \| Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Due from Related Parties	$ 271,000
Kings Hill Unit Trust [Member] \| United Kingdom [Member] \| Equity Method Investee [Member] \| Accounts Receivable [Member]
Related Party Transaction [Line Items]
Due from Related Parties		267,000
Kings Hill Unit Trust [Member] \| United Kingdom [Member] \| Equity Method Investee [Member] \| Investments in and advances to unconsolidated joint ventures [Member]
Related Party Transaction [Line Items]
Notes Receivable, Related Parties	4,700,000	18,100,000
Liberty Illinois, LP [Member] \| Chicago Milwaukee [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue	1,300,000	1,000,000	952,000
Blythe Valley JV Sarl [Member] \| United Kingdom [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue			33,000
Liberty Washington, LP [Member] \| Northern Virginia and Washington DC [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue	4,800,000	4,400,000	4,900,000
Liberty Washington, LP [Member] \| Northern Virginia and Washington DC [Member] \| Equity Method Investee [Member] \| Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Due from Related Parties	693,000	470,000
Liberty Commerz 1701 JFK Boulevard, LP [Member] \| Philadelphia [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Management Fees Revenue	2,700,000	2,400,000	$ 2,200,000
Liberty Commerz 1701 JFK Boulevard, LP [Member] \| Philadelphia [Member] \| Equity Method Investee [Member] \| Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Due from Related Parties	407,000	409,000
Liberty Commerz 1701 JFK Boulevard, LP [Member] \| Philadelphia [Member] \| Equity Method Investee [Member] \| Investments in and advances to unconsolidated joint ventures [Member]
Related Party Transaction [Line Items]
Due to Related Parties	59,000	59,000
Liberty Property 18th & Arch [Member] \| Philadelphia [Member] \| Equity Method Investee [Member] \| Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Due to Related Parties		554,000
Liberty Property 18th & Arch [Member] \| Philadelphia [Member] \| Equity Method Investee [Member] \| Other Liabilities [Member]
Related Party Transaction [Line Items]
Due to Related Parties	1,200,000
Liberty Property 18th & Arch [Member] \| Philadelphia [Member] \| Equity Method Investee [Member] \| Other Income [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	$ 5,100,000	1,800,000
Cambridge Medipark Ltd [Member] \| United Kingdom [Member] \| Equity Method Investee [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Rate	0.00%
Cambridge Medipark Ltd [Member] \| United Kingdom [Member] \| Equity Method Investee [Member] \| Investments in and advances to unconsolidated joint ventures [Member]
Related Party Transaction [Line Items]
Notes Payable, Related Parties	$ 2,700,000	$ 2,900,000