Related Party Transactions - Additional Information (Detail)		1 Months Ended	12 Months Ended
	Dec. 08, 2016	Aug. 31, 2016 USD ($) a	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transactions [Abstract]
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, maximum percentage			6.00%
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, amount			$ 349,500	$ 329,000	$ 400,000
Deferred compensation, employee contribution, percentage			2.00%
Deferred compensation, employer contribution, percentage			3	3	3
Deferred compensation, company contribution, amount			$ 228,500	$ 250,800	$ 224,900
Deferred compensation, cumulative unfunded liability			2,400,000	2,100,000
Ancillary costs and expenses			8,100,000	7,200,000	8,200,000
Liability due to the Saul Organization for the company's share of these ancillary costs and expenses			993,200	829,000
Automatic renewal period	12 months
Insurance commissions and fees expense			$ 288,400	$ 360,500	$ 443,500
Initial purchase price		$ 8,800,000
Area of real estate property (in square feet) | a		14.3