Rates and Other Regulatory Activities - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) dekatherm / d Dekatherm mi	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Rates and Other Regulatory Activities [Line Items]
Restricted Payment	$ 289,400
Regulatory Assets	123,967	$ 124,592
Revenues	569,968	488,198	$ 479,605
COVID-19 Regulatory Asset	$ 2,300	1,900
Peninsula Pipeline [Member] | Callahan Project [Member]
Rates and Other Regulatory Activities [Line Items]
Number of Pipeline Miles | mi	26
Diameter of Pipe | mi	16
Florida Public Utilities Company [Member]
Rates and Other Regulatory Activities [Line Items]
COVID-19 Settlement Amount	$ 2,100
Eastern Shore Gas Company | Del-Mar Pathway Project [Domain]
Rates and Other Regulatory Activities [Line Items]
firm natural gas transportation deliverability | dekatherm / d	14,300
Eastern Shore Gas Company | Del-Mar Pathway Project [Member]
Rates and Other Regulatory Activities [Line Items]
Number of Pipeline Miles | mi	6
number of customers	4
Number of Mainline Pipeline Miles | mi	13
Hurricane Michael
Rates and Other Regulatory Activities [Line Items]
Regulatory Liability, Amortization Period, Low Range	6 years
Regulatory Liability, Amortization Period, Revised	10 years
TCJA
Rates and Other Regulatory Activities [Line Items]
Regulatory Liability, Amortization Period, Low Range	5 years
Regulatory Liability, Amortization Period, Revised	80 years
Peninsula Pipeline Company | Winter Haven Expansion
Rates and Other Regulatory Activities [Line Items]
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	6,800
Peninsula Pipeline Company | Beachside Expansion
Rates and Other Regulatory Activities [Line Items]
Number of Mainline Pipeline Miles | mi	11
Additional Firm Natural Gas Transportation Deliverability | Dekatherm	10,176
Delmarva
Rates and Other Regulatory Activities [Line Items]
COVID-19 Settlement Amount	$ 300
Florida Public Utilities Company [Member]
Rates and Other Regulatory Activities [Line Items]
Business Acquisition Premium Paid	34,200
Eastern Shore Gas Company
Rates and Other Regulatory Activities [Line Items]
One time bill credit related to TCJA	900
Maryland Division [Member]
Rates and Other Regulatory Activities [Line Items]
One time bill credit related to TCJA	365
Sandpiper [Member]
Rates and Other Regulatory Activities [Line Items]
One time bill credit related to TCJA	608
Delaware natural gas division [Member]
Rates and Other Regulatory Activities [Line Items]
One time bill credit related to TCJA	1,500
Elkton Gas [Member]
Rates and Other Regulatory Activities [Line Items]
One time bill credit related to TCJA	47
Elkton Gas [Member]
Rates and Other Regulatory Activities [Line Items]
Revenues	$ 7,105	$ 2,399
Elkton Gas [Member] | Regulated Energy [Member]
Rates and Other Regulatory Activities [Line Items]
Number of customers acquired through acquisition	7,000