Acquisitions - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Business Combination, Separately Recognized Transactions [Line Items]
Number of Miles of Distribution Mains	150	160
Equity Issued in Business Combination, Fair Value Disclosure	$ 366,400,000
Proceeds from Issuance of Senior Long-Term Debt	550,000,000
Business Acquisition, Transaction Costs	4,100,000
Business Combination, Acquisition Related Costs	15,900,000
Revenues	787,200,000	$ 670,600,000	$ 680,700,000
Operating Income	228,200,000	150,800,000	142,900,000
Transaction-related expenses	4,000,000.0	10,400,000	0
Regulated Energy [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Revenues	583,400,000	473,600,000	429,400,000
Operating Income	196,200,000	126,200,000	$ 115,300,000
Common Stock [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Proceeds from Issuance of Senior Long-Term Debt	4,400,000
Florida City Gas
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Consideration Transferred	$ 922,800,000
Number of customers acquired through acquisition	123,000
Number of Miles of Distribution Mains	3,982
Number of Miles of Transmission Pipe	80
Business Combination, Integration Related Costs		10,400,000
Transaction-related expenses	$ 4,000,000.0	7,500,000
Property, Plant and Equipment, Acquired During Period	454,400,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	460,900,000
Florida City Gas | Regulated Energy [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Revenues	140,300,000	12,100,000
Operating Income	13,500,000	$ (3,300,000)
J.T. Lee and Son's
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Consideration Transferred	$ 3,900,000
Number of customers acquired through acquisition	3,000
Business Combination, Contingent Consideration, Liability	$ 300,000
Gallons acquired through acquisition	800,000
Bulk Plant Storage Acquired Through Acquisition	60,000
Property, Plant and Equipment, Acquired During Period	$ 2,700,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	900,000
Business Combination, Working Capital	200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	$ 100,000