Acquisitions - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Business Combination, Separately Recognized Transaction [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	550,000,000.0
Business Combination, Transaction Cost, Excluding Separately Recognized Transaction	4,100,000
Business Combination, Acquisition-Related Cost, Expense	15,900,000
Revenues	930,000,000.0	$ 787,200,000	$ 670,600,000
Operating Income	255,900,000	228,200,000	150,800,000
Transaction-related expenses	1,200,000	4,000,000.0	10,400,000
Regulated Energy [Member]
Business Combination, Separately Recognized Transaction [Line Items]
Revenues	687,800,000	583,400,000	473,600,000
Operating Income	222,000,000.0	196,200,000	126,200,000
Common Stock [Member]
Business Combination, Separately Recognized Transaction [Line Items]
Proceeds from Issuance of Senior Long-Term Debt	4,400,000
Florida City Gas
Business Combination, Separately Recognized Transaction [Line Items]
Business Combination, Consideration Transferred	922,800,000
Business Combination, Integration-Related Cost, Expense		10,400,000
Transaction-related expenses	1,200,000		$ 4,000,000.0
Property, Plant and Equipment, Acquired During Period	454,400,000
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill	460,900,000
Florida City Gas | Regulated Energy [Member]
Business Combination, Separately Recognized Transaction [Line Items]
Revenues	170,400,000	140,300,000
Operating Income	$ 5,200,000	$ 13,500,000