CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Electric	$ 981,178	$ 921,093	$ 1,037,053
Gas	276,732	270,916	268,599
Total Revenues	1,257,910	1,192,009	1,305,652
Operating Expenses
Cost of sales	318,020	272,883	410,349
Operating, general and administrative	318,229	307,119	294,803
Property and other taxes	171,888	171,259	162,614
Depreciation and depletion	172,923	174,476	166,137
Total Operating Expenses	981,060	925,737	1,033,903
Operating Income	276,850	266,272	271,749
Interest Expense, net	(95,068)	(91,988)	(92,263)
Other Income (Expense), net	413	3,966	(3,415)
Income Before Income Taxes	182,195	178,250	176,071
Income Tax Benefit (Expense)	19,925	18,710	(13,368)
Net Income	$ 202,120	$ 196,960	$ 162,703
Average Common Shares Outstanding	50,428,560	49,984,562	48,557,599
Basic Earnings per Average Common Share	$ 4.01	$ 3.94	$ 3.35
Diluted Earnings per Average Common Share	$ 3.98	$ 3.92	$ 3.34