Derivative Instruments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	$ 1,967,000	$ 0
Energy Marketing Contract Liabilities, Current	(439,000)	(1,844,000)
Notional Amount of Nonderivative Instruments	$ 100,000,000.0
Number of short-term lines of Credit, rate swap	3
Interest Rate Swap [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 100,000
Designated as Hedging Instrument [Member] | Mark To Market Energy Assets [Member] | Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	1,967,000	0
Designated as Hedging Instrument [Member] | Mark-to-market energy liabilities [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Energy Marketing Contract Liabilities, Current	(13,000)	0
Designated as Hedging Instrument [Member] | Mark-to-market energy liabilities [Member] | Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contract Liabilities, Current	(426,000)	(1,844,000)
Sharp Energy Inc [Member]
Derivative [Line Items]
Receivables from Brokers-Dealers and Clearing Organizations	(177,000)	$ (2,317,000)
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 1,000,000.0
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimate of Time to Transfer	12 months
Interest Rate Swap Rate, High Range [Member]
Derivative [Line Items]
Fixed Swap Rate	38.75%
Interest Rate Swap Rate, Low Range [Member]
Derivative [Line Items]
Fixed Swap Rate	26.15%