Rates and Other Regulatory Activities - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) Dekatherm mi	Dec. 31, 2022 USD ($)
Rates and Other Regulatory Activities [Line Items]
COVID-19 Regulatory Asset	$ 500	$ 1,200
Interim Rates	7,700
Permanent Rates	24,100
Annual Rate Case Recovery	17,200
Gas Utility Access and Replacement Directive Related Capital Expenditures	205,000
Florida Public Utilities Company [Member]
Rates and Other Regulatory Activities [Line Items]
COVID-19 Settlement Amount	2,100
Delaware natural gas division [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	12,086	12,230
Maryland Division [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	3,614	3,703
Sandpiper [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	3,515	3,597
Florida Public Utilities Company [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	26,788	27,179
FPU electric division [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	4,818	4,993
Eastern Shore Gas Company [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	34,190	34,190
Elkton Gas [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	$ 1,035	$ 1,059
Beachside Expansion | Peninsula Pipeline Company [Member]
Rates and Other Regulatory Activities [Line Items]
Number of Mainline Pipeline Miles | mi	11.3
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	10,176
Twin Lakes Expansion | Peninsula Pipeline Company [Member]
Rates and Other Regulatory Activities [Line Items]
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	2,400
Lake Wales Pipeline Acquisition | Peninsula Pipeline Company [Member]
Rates and Other Regulatory Activities [Line Items]
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	9,000
Ocean City Maryland Reinforcement | Maryland Natural Gas [Member]
Rates and Other Regulatory Activities [Line Items]
Number of Mainline Pipeline Miles | mi	5.7
Newberry Expansion | Peninsula Pipeline Company [Member]
Rates and Other Regulatory Activities [Line Items]
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	8,000