Condensed Consolidated Statements of Income (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Revenues
Regulated Energy	$ 102,955,000	$ 103,618,000
Unregulated Energy and other	49,755,000	56,846,000
Total Operating Revenues	152,710,000	160,464,000
Operating Expenses
Regulated Energy cost of sales	34,832,000	36,516,000
Unregulated Energy and other cost of sales	18,036,000	24,411,000
Operations	35,992,000	35,413,000
Maintenance	3,836,000	3,680,000
Depreciation and amortization	12,252,000	10,928,000
Other taxes	5,649,000	5,392,000
Total Operating Expenses	110,597,000	116,340,000
Operating Income	42,113,000	44,124,000
Other income (expense), net	3,318,000	(57,000)
Interest charges	5,814,000	5,628,000
Income from Continuing Operations Before Income Taxes	39,617,000	38,439,000
Income Taxes on Continuing Operations	10,591,000	9,625,000
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	29,026,000	28,814,000
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	(96,000)	(150,000)
Income from Continuing Operations	$ 28,930,000	$ 28,664,000
Weighted Average Common Shares Outstanding:
Basic (shares)	16,414,773	16,384,927
Diluted (shares)	16,471,827	16,432,852
Basic Earnings Per Share of Common Stock:
Income (Loss) from Continuing Operations, Per Basic Share	$ 1.77	$ 1.76
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	(0.01)	(0.01)
Basic (in dollars per share)	1.76	1.75
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	1.77	1.75
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	(0.01)	(0.01)
Diluted (in dollars per share)	$ 1.76	$ 1.74
Retained Earnings [Member]
Operating Expenses
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 29,026,000	$ 28,814,000
Income from Continuing Operations	$ 28,930,000	$ 28,664,000