CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating revenues
Electric	$ 190,811	$ 182,001
Natural gas	50,357	41,492
Other	247	306
Total operating revenues	241,415	223,799
Operating expenses
Electric fuel and purchased power, non-affiliates	4,170	3,447
Purchased power, affiliates	98,942	99,167
Cost of natural gas sold and transported	30,985	26,879
Operating and maintenance expenses	41,676	38,500
Conservation program expenses	2,992	3,502
Depreciation and amortization	18,855	17,009
Taxes (other than income taxes)	6,394	6,381
Total operating expenses	204,014	194,885
Operating income	37,401	28,914
Other income, net	115	500
Allowance for funds used during construction - equity	946	999
Interest charges and financing costs
Interest charges - includes other financing costs of $381 and $426, respectively	6,855	6,015
Allowance for funds used during construction - debt	(409)	(86)
Total interest charges and financing costs	6,446	5,929
Income before income taxes	32,016	24,484
Income taxes	12,331	9,606
Net income	$ 19,685	$ 14,878