Increase (Decrease) In Carrying Value Of Disposed Properties

No definition available.

Name:	gov_IncreaseDecreaseInCarryingValueOfDisposedProperties
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

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)
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ 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://www.xbrl.org/2003/role/presentationRef
-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:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsHeldforsaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gov_OneBuildingDispositionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=gov_AlbuquerqueNMMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_OfficeBuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_StatementGeographicalAxis=gov_FallsChurchVAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Real Estate Properties - Disposition Activities (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2017 USD ($) ft² property building	Sep. 30, 2017 USD ($) property building	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) property building	Sep. 30, 2016 USD ($)	Oct. 05, 2017 USD ($) ft² property building	Dec. 31, 2016 USD ($)
Real Estate Properties [Line Items]
Number of properties \| property		74		74
Number of buildings \| building		96		96
Net book value		$ 1,598,642		$ 1,598,642			$ 1,591,956
Loss on impairment of real estate		230	$ 0	230	$ 0
Discontinued Operations, Held-for-sale \| One building \| Albuquerque, NM \| Office Building
Real Estate Properties [Line Items]
Aggregate sale price of properties sold, excluding closing costs				$ 2,000
Loss on impairment of real estate		230
Discontinued operations \| One building \| Falls Church, VA \| Office Building
Real Estate Properties [Line Items]
Number of properties \| property	1
Number of buildings \| building	1
Rentable square feet of properties (in square feet) \| ft²	164,746
Net book value	$ 12,901
Aggregate sale price of properties sold, excluding closing costs	$ 13,523
Increase in carrying value of property included in discontinued operations		$ (619)
Subsequent Event \| Discontinued Operations, Held-for-sale \| One building \| Albuquerque, NM \| Office Building
Real Estate Properties [Line Items]
Number of properties \| property						1
Number of buildings \| building						1
Rentable square feet of properties (in square feet) \| ft²						29,045
Net book value						$ 1,885