Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 12,365,000	$ 7,316,000
Acquired finite-lived intangible assets, weighted average useful life		11 years
Goodwill		$ 32,668,000	21,568,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		800,000
Amortization of intangible assets		400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four		900,000
Amortization of intangible assets, 2019		1,200,000
Amortization of intangible assets, 2020		1,153,466
Amortization of intangible assets, 2022		800,000
Customer list
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 9,391,000	4,801,000
Customer list | Minimum
Goodwill [Line Items]
Amortized period of acquired intangible assets		5 years
Customer list | Boulden [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 4,600,000
Noncompete Agreements [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		2,252,000	$ 1,793,000
Noncompete Agreements [Member] | Boulden [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		500,000
Boulden [Member] | Unregulated Energy
Goodwill [Line Items]
Goodwill	[1]	$ 11,200,000

[1] ⁽³⁾ Mid-Atlantic Propane Operations goodwill balance includes $11.2 million recognized as a result of the purchase of the operating assets of Boulden in December 2019.