Contract Price for Sale of Real Estate

No definition available.

Name:	jbgs_ContractPriceforSaleofRealEstate
Namespace Prefix:	jbgs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Gain (loss) from cash and land contribution to a real estate venture.

+ References

No definition available.

+ Details

Name:	jbgs_GainLossFromRealEstateVentureCashAndLandContribution
Namespace Prefix:	jbgs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of real estate properties sold.

+ References

No definition available.

+ Details

Name:	jbgs_NumberOfRealEstatePropertiesSold
Namespace Prefix:	jbgs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of real estate ventures.

+ References

No definition available.

+ Details

Name:	jbgs_NumberOfRealEstateVentures
Namespace Prefix:	jbgs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of preferred return subordinated to counter-party ownership interest.

+ References

No definition available.

+ Details

Name:	jbgs_PercentagePreferredReturnSubordinatedToOwnershipInterest
Namespace Prefix:	jbgs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of real estate venture promote interest paid during the period.

+ References

No definition available.

+ Details

Name:	jbgs_RealEstateVenturePromoteInterestPaid
Namespace Prefix:	jbgs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Area of land held.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 35
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=124268079&loc=d3e32787-111569

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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/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=123570139&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 cash outflow associated with the purchase of real estate held-for-investment and real estate joint ventures.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585

+ Details

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

- Definition

The cash inflow from a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

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

- Definition

The amount of revenue derived from managing real estate properties.

+ References

No definition available.

+ Details

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

- Definition

The carrying amount of investments in unconsolidated real estate and other joint ventures not separately presented. This includes direct and indirect 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=120400017&loc=d3e572229-122910

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jbgs_InvestmentsinUnconsolidatedRealEstateVenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jbgs_FortressInvestmentGroupRealEstateVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=jbgs_FortressInvestmentGroupLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=jbgs_MortgageLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jbgs_PacificLifeInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jbgs_J.p.MorganGlobalAlternativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=jbgs_NonEmployeeTrusteesAndCertainExecutivesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	dei_LegalEntityAxis=jbgs_InstitutionalInvestorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jbgs_LandmarkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Investments in Unconsolidated Real Estate Ventures - Narratives (Details) $ in Thousands	1 Months Ended		3 Months Ended			12 Months Ended
	Apr. 30, 2022 USD ($) ft² property	Apr. 30, 2021 USD ($) ft² item	Sep. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Payments for investments in unconsolidated real estate ventures						$ 91,591	$ 41,780	$ 14,639
Borrowings under mortgage loans						179,744	190,000	580,105
Investments in unconsolidated real estate ventures						299,881	462,885
Impairment of Real Estate								7,800
Investments in Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Property management fee revenue						$ 24,000	23,700	$ 25,500
Fortress Investment Group Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Area of land \| ft²	1,600,000
Gross sales price	$ 580,000
Number of real estate properties sold \| property	4
Ownership interest (as percent)	33.50%
Payments for investments in unconsolidated real estate ventures	$ 66,100
Percentage of preferred return subordinated to counter-party ownership interest	15.00%
Investments in unconsolidated real estate ventures	$ 0
Fortress Investment Group Real Estate Venture \| Fortress Investment Group LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (as percent)	66.50%
Payments for investments in unconsolidated real estate ventures	$ 131,000
Fortress Investment Group Real Estate Venture \| Fortress Investment Group LLC \| Mortgage Loan
Schedule of Equity Method Investments [Line Items]
Principal amount	458,000
Borrowings under mortgage loans	$ 402,000
CIM/PacLife [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated real estate ventures					$ 0
CIM/PacLife [Member] \| The Marriott Wardman Park hotel
Schedule of Equity Method Investments [Line Items]
Impairment loss					$ 6,500
J.P. Morgan Global Alternatives ("J.P. Morgan")
Schedule of Equity Method Investments [Line Items]
Ownership interest (as percent)						50.00%
Investments in unconsolidated real estate ventures						$ 64,803	52,769
J.P. Morgan Global Alternatives ("J.P. Morgan") \| Potomac Yard Mixed Use Development
Schedule of Equity Method Investments [Line Items]
Ownership interest (as percent)		50.00%
Number of real estate ventures \| item		2
Gain from contribution to real estate ventures		$ 11,300
Real Estate Venture Promote Interest Paid				$ 17,500
Area of Real Estate Property \| ft²		2,000,000.0
J.P. Morgan Global Alternatives ("J.P. Morgan") \| Potomac Yard Mixed Use Development \| Non-employee Trustees and Certain Executives
Schedule of Equity Method Investments [Line Items]
Real Estate Venture Promote Interest Paid				$ 4,200
J.P. Morgan Global Alternatives ("J.P. Morgan") \| Potomac Yard Landbay G
Schedule of Equity Method Investments [Line Items]
Area of Real Estate Property \| ft²		700,000
J.P. Morgan Global Alternatives ("J.P. Morgan") \| Potomac Yard Landbay F \| Institutional Investor
Schedule of Equity Method Investments [Line Items]
Area of Real Estate Property \| ft²		1,300,000
Landmark
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated real estate ventures						4,809	28,298
Landmark \| L'Enfant Plaza
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated real estate ventures						0
Impairment loss			$ 15,400				$ 23,900
Landmark \| Rosslyn Gateway assets
Schedule of Equity Method Investments [Line Items]
Impairment of Real Estate						$ 3,900