CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Electric	$ 238,342,000	$ 266,239,000
Gas	103,160,000	101,073,000
Total Revenues	341,502,000	367,312,000
Operating Expenses
Cost of sales	96,077,000	119,817,000
Operating, general and administrative	74,345,000	78,334,000
Property and other taxes	42,813,000	39,928,000
Depreciation and depletion	43,755,000	41,461,000
Total Operating Expenses	256,990,000	279,540,000
Operating Income	84,512,000	87,772,000
Interest Expense, net	(22,970,000)	(23,400,000)
Other Expense, net	(1,129,000)	(1,128,000)
Income Before Income Taxes	60,413,000	63,244,000
Income Tax Expense	(1,914,000)	(6,677,000)
Net Income	$ 58,499,000	$ 56,567,000
Average Common Shares Outstanding	49,416,230	48,385,738
Basic Earnings per Average Common Share	$ 1.18	$ 1.17
Diluted Earnings per Average Common Share	1.18	1.17
Dividends Declared per Common Share	$ 0.550	$ 0.525