Derivative Instruments - Fair Values of Derivative Contracts Recorded in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions		Dec. 31, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current		$ 0.0	$ 0.6
Energy Marketing Contracts Assets, Total	[1]	0.0	0.7
Energy Marketing Contract Liabilities, Current		0.8	0.0
Energy Marketing Contract Liabilities, Total	[2]	1.4	0.1
Designated as Hedging Instrument [Member] | Mark-to-market energy liabilities | Propane Swap Agreement
Derivatives, Fair Value [Line Items]
Energy Marketing Contract Liabilities, Current		0.7	0.0
Designated as Hedging Instrument [Member] | Mark-to-market energy liabilities | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contract Liabilities, Current		0.7	0.1
Designated as Hedging Instrument [Member] | Mark To Market Energy Assets | Propane Swap Agreement
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current		0.0	0.6
Designated as Hedging Instrument [Member] | Mark To Market Energy Assets | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current		$ 0.0	$ 0.1

[1]  (1) There were no current derivative assets at December 31, 2025. Derivative assets, at fair value included $0.6 million in current assets in the consolidated balance sheets at December 31, 2024, with the remainder of the balance classified as long-term

[2] (1) Derivative liabilities, at fair value included $0.8 million in current liabilities in the consolidated balance sheet at December 31, 2025, with the remaining balance classified as long-term. There were no current derivative liabilities at December 31, 2024.