Variable Interest Entities (Details)	1 Months Ended		10 Months Ended
	Dec. 31, 2021 USD ($) item	Mar. 31, 2021 USD ($) item	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)
Variable Interest Entity [Line Items]
Assets	$ 6,386,206,000		$ 6,386,206,000	$ 6,079,547,000
Liabilities	$ 2,925,064,000		$ 2,925,064,000	2,342,593,000
JBG Smith, LP
Variable Interest Entity [Line Items]
Ownership interest by parent	89.50%		89.50%
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Carrying value of investments	$ 145,200,000		$ 145,200,000	$ 116,200,000
Variable Interest Entity, Primary Beneficiary | The Batley
Variable Interest Entity [Line Items]
Assets	207,200,000		207,200,000
Liabilities	792,000		792,000
Variable Interest Entity, Primary Beneficiary | 1900 Crystal Drive
Variable Interest Entity [Line Items]
Assets	58,600,000		58,600,000
Liabilities	12,000,000.0		12,000,000.0
Number of Units in Real Estate Property | item		808
Number of Towers in Real Estate Property | item		2
Ground lessee equity funding obligation		$ 17,500,000
Mezzanine loan project funding to ground lessee		104,800,000
Mezzanine loan funded to the ground lessee	34,900,000		34,900,000
Variable Interest Entity, Primary Beneficiary | 1900 Crystal Drive | Mortgages Payable
Variable Interest Entity [Line Items]
Principal amount		$ 227,000,000.0
Proceeds from issuance of mortgage loan			0
Variable Interest Entity, Primary Beneficiary | 1900 Crystal Drive | Mortgages Payable | London Interbank Offered Rate (LIBOR)
Variable Interest Entity [Line Items]
Debt Instrument basis spread on variable rate		3.00%
Variable Interest Entity, Primary Beneficiary | 2000 and 2001 South Bell Street
Variable Interest Entity [Line Items]
Assets	3,900,000		3,900,000
Liabilities	$ 1,100,000		$ 1,100,000
Number of Units in Real Estate Property | item	775		775
Number of Towers in Real Estate Property | item	2		2
Ground lessee equity funding obligation	$ 16,000,000.0		$ 16,000,000.0
Ground lessee equity funding	6,700,000		6,700,000
Mezzanine loan project funding to ground lessee	96,200,000		96,200,000
Mezzanine loan funded to the ground lessee	0		0
Variable Interest Entity, Primary Beneficiary | 2000 and 2001 South Bell Street | London Interbank Offered Rate (LIBOR)
Variable Interest Entity [Line Items]
Principal amount	$ 208,500,000		$ 208,500,000
Debt Instrument basis spread on variable rate	2.15%
Variable Interest Entity, Primary Beneficiary | 2000 and 2001 South Bell Street | Mortgages Payable
Variable Interest Entity [Line Items]
Proceeds from issuance of mortgage loan	$ 0