Debt - Summary of Amounts Outstanding under the Credit Facility (Details)	6 Months Ended
Jun. 30, 2024 USD ($) DerivativeInstrument	Dec. 31, 2023 USD ($) DerivativeInstrument
Debt
Deferred financing costs on credit facility	$ 8,740,000	$ 10,199,000
Line of credit \| Revolving credit facility
Debt
Effective interest rate	6.78%
Long-term debt, net	$ 40,000,000	62,000,000
Facility fee	0.15%
Aggregate face amount outstanding	$ 15,700,000	467,000
Line of credit \| Revolving credit facility \| Daily SOTR
Debt
SOFR at end of period	5.33%
Line of credit \| Revolving credit facility \| Other Assets Net
Debt
Deferred financing costs on credit facility	$ 8,700,000	10,200,000
Line of credit \| Term Loans
Debt
Debt, gross	720,000,000	720,000,000
Unamortized deferred financing costs and premium / discount, net	(2,390,000)	(2,828,000)
Long-term debt, net	$ 717,610,000	717,172,000
Line of credit \| Tranche A-1 Term Loan
Debt
Effective interest rate	2.70%
Debt, gross	$ 200,000,000	200,000,000
Line of credit \| Tranche A-1 Term Loan \| Forward Interest Rate Swap Effective July 2024
Debt
Derivative notional amount	$ 200,000,000.0	$ 200,000,000.0
Number of interest rate swaps \| DerivativeInstrument	2	2
Line of credit \| Tranche A-1 Term Loan \| Forward Interest Rate Swap Effective July 2024 \| Secured Overnight Financing Rate ("SOFR")
Debt
Fixed SOFR	4.00%	4.00%
Line of credit \| Tranche A-1 Term Loan \| Interest rate swap \| Secured Overnight Financing Rate ("SOFR")
Debt
Fixed SOFR	1.46%	1.46%
Line of credit \| Tranche A-2 Term Loan
Debt
Effective interest rate	3.58%
Debt, gross	$ 400,000,000	$ 400,000,000
Line of credit \| Tranche A-2 Term Loan \| Forward Interest Rate Swap Effective July 2024
Debt
Derivative notional amount	$ 200,000,000.0	$ 200,000,000.0
Number of interest rate swaps \| DerivativeInstrument	2	2
Line of credit \| Tranche A-2 Term Loan \| Forward Interest Rate Swap Effective July 2024 \| Secured Overnight Financing Rate ("SOFR")
Debt
Fixed SOFR	2.81%	2.81%
Line of credit \| Tranche A-2 Term Loan \| Interest rate swap \| Secured Overnight Financing Rate ("SOFR")
Debt
Fixed SOFR	2.29%	2.29%
Line of credit \| Tranche A-2 Term Loan \| Interest Rate Swaps Maturing July 2024
Debt
Derivative notional amount	$ 200,000,000.0	$ 200,000,000.0
Line of credit \| Tranche A-2 Term Loan \| Interest Rate Swaps Maturing January 2028
Debt
Derivative notional amount	$ 200,000,000.0	200,000,000.0
Line of credit \| 2023 Term Loan
Debt
Effective interest rate	5.31%
Debt, gross	$ 120,000,000	$ 120,000,000
Line of credit \| 2023 Term Loan \| Interest rate swap \| Secured Overnight Financing Rate ("SOFR")
Debt
Fixed SOFR	4.01%	4.01%

Represents the fixed SOFR.

No definition available.

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

- Definition

The facility fee, expressed as a percentage of the line of credit facility,

+ References

No definition available.

+ Details

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

- Definition

Represents the SOFR as of period end.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

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+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

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+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

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Balance Type:	na
Period Type:	duration

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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+ Details

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

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

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- Details

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- Details

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