Fair Value Adjustment

No definition available.

Name:	gov_FairValueAdjustment
Namespace Prefix:	gov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of buildings owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	gov_NumberOfBuildings
Namespace Prefix:	gov_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate sales price excluding closing costs, of real estate properties sold by the entity.

+ References

No definition available.

+ Details

Name:	gov_RealEstateAggregateSalesPrice
Namespace Prefix:	gov_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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

- Definition

This element represents the amount of gain (loss) on sale of properties during the reporting period net of the applicable income taxes realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-15.(a)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

+ Details

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

- 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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_RealEstateInvestmentPropertyNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Name:	us-gaap_RealEstatePropertiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=srt_OfficeBuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=gov_MinneapolisNMMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gov_OneBuildingDispositionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=gov_SaffordAZMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_StatementGeographicalAxis=gov_NewYorkNYMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_StatementGeographicalAxis=gov_SacramentoCaMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=gov_FPOTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_StatementGeographicalAxis=stpr_DC
Namespace Prefix:
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Real Estate Properties - Disposition Activities (Details) $ in Thousands	1 Months Ended		3 Months Ended				9 Months Ended
	May 31, 2018 USD ($) ft² property building	Mar. 31, 2018 USD ($) ft² property building	Sep. 30, 2018 USD ($) property building	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($) ft² property building	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) property building	Sep. 30, 2017 USD ($)	Oct. 31, 2018 property	Feb. 28, 2018 ft² property building	Dec. 31, 2017 USD ($)
Real Estate Properties [Line Items]
Number of properties \| property			105				105
Number of buildings \| building			164				164
Loss on impairment of real estate			$ 0			$ 230	$ 5,800	$ 230
Gain (loss) on sale of real estate			0			$ 0	17,329	$ 0
Net book value			$ 2,135,589				$ 2,135,589				$ 2,633,873
Office Building \| Disposal Group, Disposed of by Sale \| Minneapolis, NM \| One building
Real Estate Properties [Line Items]
Number of properties \| property		1			1
Number of buildings \| building		1			1
Rentable area of properties (in square feet) \| ft²		193,594			193,594
Aggregate sale price of properties sold, excluding closing costs		$ 20,000
Loss on impairment of real estate					$ 640
Office Building \| Disposal Group, Disposed of by Sale \| Safford, AZ \| One building
Real Estate Properties [Line Items]
Number of properties \| property										1
Number of buildings \| building										1
Rentable area of properties (in square feet) \| ft²										36,139
Aggregate sale price of properties sold, excluding closing costs					8,250
Loss on impairment of real estate					2,453
Fair value adjustment				$ 322
Office Building \| Disposal Group, Disposed of by Sale \| New York, NY \| One building
Real Estate Properties [Line Items]
Number of properties \| property	1
Number of buildings \| building	1
Rentable area of properties (in square feet) \| ft²	187,060
Aggregate sale price of properties sold, excluding closing costs	$ 118,500
Gain (loss) on sale of real estate				17,329
Office Building \| Disposal Group, Disposed of by Sale \| Sacramento, CA \| One building
Real Estate Properties [Line Items]
Number of properties \| property	1
Number of buildings \| building	1
Rentable area of properties (in square feet) \| ft²	110,500
Aggregate sale price of properties sold, excluding closing costs	$ 10,755
Loss on impairment of real estate				$ 6	$ 3,023
FPO Transaction \| Disposal Group, Disposed of by Sale
Real Estate Properties [Line Items]
Number of properties \| property			3				3
Number of buildings \| building			3				3
Net book value			$ 24,566				$ 24,566
Subsequent Event \| Office Building \| Disposal Group, Disposed of by Sale \| Washington D.C. \| One building
Real Estate Properties [Line Items]
Number of properties \| property									1