Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Operating revenues:
Electric	$ 134,363	$ 142,641	$ 546,808	$ 582,043
Gas	15,113	19,818	36,997	47,051
Other	1,839	2,085	8,539	8,107
Total operating revenues	151,315	164,544	592,344	637,201
Operating revenue deductions:
Fuel and purchased power	37,840	48,977	158,723	208,477
Cost of natural gas sold and transported	7,561	11,423	15,639	23,403
Regulated operating expenses	27,845	28,551	112,845	111,371
Other operating expenses	961	805	3,466	3,076
Maintenance and repairs	10,218	10,267	48,474	46,784
Merger related expenses	4,248		4,499
Depreciation and amortization	20,403	20,020	80,933	75,264
Provision for income taxes	8,675	8,884	34,592	36,108
Other taxes	10,321	10,904	38,595	37,493
Total operating revenue deductions	128,072	139,831	497,766	541,976
Operating income	23,243	24,713	94,578	95,225
Other income and (deductions):
Allowance for equity funds used during construction	1,704	978	5,577	6,147
Interest income	9	11	144	20
Benefit for other income taxes	36	113	910	237
Other - non-operating expense, net	(408)	(698)	(2,887)	(1,655)
Total other income	1,341	404	3,744	4,749
Interest charges:
Long-term debt	11,298	10,751	44,348	41,283
Short-term debt	62	73	255	181
Allowance for borrowed funds used during construction	(1,053)	(564)	(3,333)	(3,320)
Other	268	220	1,083	995
Total interest charges	10,575	10,480	42,353	39,139
Net income	$ 14,009	$ 14,637	$ 55,969	$ 60,835
Weighted average number of common shares outstanding - basic (in shares)	43,882	43,531	43,758	43,395
Weighted average number of common shares outstanding - diluted (in shares)	43,937	43,612	43,777	43,460
Total earnings per weighted average share of common stock - basic and diluted (in dollars per share)	$ 0.32	$ 0.34	$ 1.28	$ 1.40
Dividends declared per share of common stock (in dollars per share)	$ 0.26	$ 0.26	$ 1.04	$ 1.03