Acquisitions and Divestitures (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Income Tax Expense (Benefit)	$ 6,334	$ 5,738
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	(6)	(111)
Revenues	191,187	152,690
Operating Income (Loss)	51,597	42,134
Unregulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Income (Loss)	19,105	13,862
Regulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Income (Loss)	32,864	$ 27,888
Elkton Gas [Member] | Regulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	15,900
Revenues	2,600
Operating Income (Loss)	$ 600
Number of customers acquired through acquisition	7,000
Business Combination, Consideration Transferred	$ 15,600
Business Combination, Working Capital	600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	2,600
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	4,300
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Regulatory Liabilities	2,600
Western Natural Gas [Member] | Unregulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	3,500
Revenues	800
Operating Income (Loss)	200
Business Combination, Consideration Transferred	6,700
Business Combination, Working Capital	300
Business Combination, Contingent Consideration, Liability	300
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	1,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	$ 1,400