Discontinued Operations - Additional Information (Detail) - USD ($)		1 Months Ended			9 Months Ended	12 Months Ended
	Feb. 10, 2017	Sep. 30, 2020	Nov. 30, 2019	May 31, 2018	Sep. 30, 2019	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Costs incurred related to environmental remediation					$ 359,000
Environmental Incident 1994 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accrual for environmental loss contingencies, period increase		$ (856,000)				$ 846,000
Environmental remediation						$ 1,043,000
Costs incurred related to environmental remediation		187,000
Environmental remediation cost of accrual, payment in 2021 and beyond		$ 480,000
Terminal [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price	$ 23,000,000
Reduced sales price	$ 1,040,000		$ 1,040,000	$ 1,040,000
Estimated cost of the construction				$ 1,923,284
Percentage of obligation on cost in excess of estimated cost				50.00%
Entities obligation on cost in excess of initial estimated cost				$ 441,642
Maximum additional obligation			104,000	$ 104,000
Entities obligation on cost in excess of actual cost			1,894,000
Actual cost of the project			$ 427,000
Percentage of obligation on cost in excess of actual cost			50.00%