Acquisitions and Divestitures (Details) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Depreciation and Amortization				$ 146		$ 291
Deferred Income Tax Expense (Benefit)					$ 12,232	7,746
Disposal Group, Including Discontinued Operation, Revenue	[1]	$ 3		41,280	23	118,302
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	[1]	10		40,539	1	115,701
Disposal Group, Including Discontinued Operation, Operating Expense		$ 39		1,470	$ 197	3,460
Number of Disposal Transactions		4			4
Proceeds from Divestiture of Businesses					$ 23,100
Disposal Group, Including Discontinued Operation, Operating Income (Loss)		$ (46)		(729)	(175)	(859)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax					5,500
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax		(52)		(830)	(204)	(1,025)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax, Incremental		200			200
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax		295		(610)	184	(757)
Settlement Gain		130		130	130	130
Disposal Group, Including Discontinued Operation, Interest Expense		(6)		(101)	(29)	(166)
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation		(147)		(220)	(188)	(268)
Revenues		97,051		94,542	249,741	255,005
Operating Income (Loss)		17,977		18,165	60,111	62,287
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax			$ 7,300		7,500
Regulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Income (Loss)		18,006		18,028	45,894	47,769
PESCO [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Revenue		4,900			14,800
Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain Loss From Discontinued Operations		295		(610)	184	(757)
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Income Tax Expense (Benefit)				(1,021)		375
Settlement Gain				(97)		(681)
Business Combination, Working Capital		8,000			8,000
Unregulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Income (Loss)		281		$ (771)	14,142	$ 14,486
Elkton Gas [Member] | Regulated Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Acquisition, Purchase Price					$ 15,000
Number of customers acquired through acquisition					7,000
Boulden [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		8,300			$ 8,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		5,100			5,100
Goodwill, Acquired During Period					11,200
Revenues		800			3,600
Operating Income (Loss)		100			$ 1,400
Number of customers acquired through acquisition					5,200
Business Combination, Consideration Transferred					$ 24,600
Business Combination, Working Capital		200			200
Business Combination, Contingent Consideration, Liability		$ 600			$ 600

[1] ⁽¹⁾ Included in operating revenues and cost of sales for the three and six months ended June 30, 2019, is $4.9 million and $14.8 million, respectively, representing amounts which had been previously eliminated in consolidation related to intercompany activity that continued with the buyers after the disposition of the assets of PESCO.