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Related Party Transactions - Additional Information (Detail)			1 Months Ended	12 Months Ended
	Jun. 30, 2021 shares	May 09, 2018 shares	Aug. 31, 2016 a	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 05, 2021 a	Nov. 05, 2019 a
Related Party Transaction [Line Items]
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, maximum percentage				6.00%	6.00%	6.00%
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, amount				$ 404,300	$ 302,000	$ 322,200
Deferred compensation, employee contribution, percentage				2.00%
Deferred compensation, employer contribution, percentage				3	3	3
Deferred compensation, company contribution, amount				$ 238,400	$ 241,300	$ 345,200
Deferred compensation, cumulative unfunded liability				3,200,000	2,900,000
Ancillary costs and expenses				8,000,000	7,400,000	8,400,000
Liability due to the Saul Organization for the company's share of these ancillary costs and expenses				1,100,000	782,700
Insurance commissions and fees expense				$ 397,900	$ 427,700	$ 399,600
BF Saul Real Estate Investment Trust | Contribution Agreement
Related Party Transaction [Line Items]
Area of land | a								10.3
BF Saul Real Estate Investment Trust | Ashbrook Marketplace
Related Party Transaction [Line Items]
Area of real estate property | a			13.7
Limited partnership units issued (in shares) | shares	93,674	176,680
BF Saul Real Estate Investment Trust | Twinbrook Metro Station Leasehold Interest | Contribution Agreement
Related Party Transaction [Line Items]
Area of land | a							1.3	1.3

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