CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenues:
Gas	$ 181,200	$ 202,600	$ 201,400
Electric	196,100	218,000	218,700
Other	6,100	6,200	5,700
Total Operating Revenues	383,400	426,800	425,800
Operating Expenses:
Cost of Gas Sales	77,600	100,700	104,000
Cost of Electric Sales	108,000	132,500	137,900
Operation and Maintenance	66,300	67,100	64,600
Depreciation and Amortization	46,600	45,700	42,100
Taxes Other Than Income Taxes	19,600	17,700	17,200
Total Operating Expenses	318,100	363,700	365,800
Operating Income	65,300	63,100	60,000
Interest Expense, net	22,500	21,900	20,900
Other Expense (Income), net	300	(500)	400
Income Before Income Taxes	42,500	41,700	38,700
Income Taxes	15,354	15,443	13,995
Net Income Applicable to Common Shares	$ 27,100	$ 26,300	$ 24,700
Earnings per Common Share-Basic and Diluted	$ 1.94	$ 1.89	$ 1.79
Weighted Average Common Shares Outstanding-(Basic and Diluted)	14.0	13.9	13.8