CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating revenues
Electric	$ 216,366	$ 216,309
Natural gas	56,500	48,347
Other	278	275
Total operating revenues	273,144	264,931
Operating expenses
Electric fuel and purchased power, non-affiliates	2,898	2,873
Purchased power, affiliates	101,311	106,458
Cost of natural gas sold and transported	28,723	25,987
Operating and maintenance expenses	50,344	49,184
Conservation expenses	2,978	3,054
Depreciation and amortization	30,587	27,049
Taxes (other than income taxes)	7,313	6,873
Total operating expenses	224,154	221,478
Operating income	48,990	43,453
Other (expense), net	(359)	(432)
Allowance for funds used during construction — equity	1,855	1,287
Interest charges and financing costs
Interest charges — includes other financing costs of $478 and $456, respectively	9,595	8,682
Allowance for funds used during construction — debt	(836)	(550)
Total interest charges and financing costs	8,759	8,132
Income before income taxes	41,727	36,176
Income taxes	10,310	13,757
Net income	$ 31,417	$ 22,419