Percentage of interests acquired at the acquisition date.

No definition available.

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

- Definition

Percentage of subordinated interest held through an unconsolidated real estate venture.

+ References

No definition available.

+ Details

Name:	jbgs_SubordinatedOwnershipInterest
Namespace Prefix:	jbgs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

+ Details

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

- Definition

Amount of other-than-temporary decline in value that has been recognized against investment accounted for under equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481664/323-10-45-1

+ 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://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

+ Details

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

Investments in Unconsolidated Real Estate Ventures - Summary of Composition of Investments (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2022	Dec. 31, 2024 USD ($) building property	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures		$ 93,654	$ 264,281
Difference between the investments in unconsolidated real estate ventures and the net book value of the underlying assets		$ 10,600	8,700
Number of Real Estate Properties \| property		38
One Commercial Building
Investments in Unconsolidated Real Estate Ventures
Subordinated interest		10.00%
Number of Real Estate Properties \| building		1
Atlantic Plumbing
Investments in Unconsolidated Real Estate Ventures
Ownership Percentage Acquired	36.00%
J.P. Morgan Global Alternatives ("J.P. Morgan")
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		50.00%
Total investments in unconsolidated real estate ventures		$ 74,188	72,742
4747 Bethesda Avenue
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		20.00%
Total investments in unconsolidated real estate ventures		$ 10,813	13,118
Brandywine Realty Trust
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		30.00%
Total investments in unconsolidated real estate ventures		$ 6,954	13,681
Prudential Global Investment Management ("PGIM")
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		50.00%
Total investments in unconsolidated real estate ventures		$ 678	163,375
Landmark Partners ("Landmark")
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		18.00%
Total investments in unconsolidated real estate ventures		$ 552	605
CBREI Venture
Investments in Unconsolidated Real Estate Ventures
Ownership interest (as percent)		10.00%
Total investments in unconsolidated real estate ventures		$ 169	180
Other
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures		300	580
Certain Ventures
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures		0	0
Development parcels \| Brandywine Realty Trust
Investments in Unconsolidated Real Estate Ventures
Impairment loss		6,700
Central Place Tower \| Prudential Global Investment Management ("PGIM")
Investments in Unconsolidated Real Estate Ventures
Impairment loss			25,300
1101 17th Street \| Canadian Pension Plan Investment Board (CPPIB)
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures		0
L'Enfant Plaza Assets and the Rosslyn Gateway Assets \| Landmark Partners ("Landmark") \| Loss from unconsolidated real estate ventures, net
Investments in Unconsolidated Real Estate Ventures
Impairment loss				$ 19,300
L'Enfant plaza assets \| Landmark Partners ("Landmark")
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures		$ 0
Foundry \| CBREI Venture
Investments in Unconsolidated Real Estate Ventures
Total investments in unconsolidated real estate ventures			0
Impairment loss			$ 3,300