CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Operating revenues:
Electric	$ 157,118	$ 146,620	$ 404,955	$ 366,469	$ 521,397	$ 469,103
Gas	5,052	5,403	33,344	36,480	47,750	52,993
Water	501	508	1,353	1,377	1,780	1,808
Other	1,613	1,555	4,453	4,136	5,992	5,427
Total operating revenues	164,284	154,086	444,105	408,462	576,919	529,331
Operating revenue deductions:
Fuel and purchased power	54,316	57,286	155,761	152,225	202,835	197,783
Cost of natural gas sold and transported	1,225	1,554	15,977	18,929	23,662	28,978
Regulated operating expenses	23,299	20,309	62,100	58,497	82,895	77,152
Other operating expenses	507	481	1,630	1,448	2,131	1,962
Maintenance and repairs	9,891	8,722	29,673	26,129	40,315	34,343
Depreciation and amortization	14,757	14,622	48,978	41,394	66,240	54,441
Provision for income taxes	15,672	11,934	28,529	26,263	32,737	29,379
Other taxes	8,167	7,305	24,026	21,347	30,408	26,927
Total operating revenue deductions	127,834	122,213	366,674	346,232	481,223	450,965
Operating income	36,450	31,873	77,431	62,230	95,696	78,366
Other income and (deductions):
Allowance for equity funds used during construction	82	840	152	4,493	197	6,636
Interest income	29	30	68	152	93	189
Benefit/(provision) for other income taxes	20	14	53	(78)	67	(310)
Other - non-operating expense, net	(522)	(245)	(981)	(747)	(1,273)	(1,030)
Total other income and (deductions)	(391)	639	(708)	3,820	(916)	5,485
Interest charges:
Long-term debt	10,654	10,757	31,927	31,325	42,561	41,951
Trust preferred securities				2,090		3,152
Short-term debt	23	114	69	604	96	748
Allowance for borrowed funds used during construction	(77)	(771)	(158)	(5,616)	(177)	(7,326)
Other	275	(569)	(1,396)	(1,289)	(2,440)	(1,537)
Total interest charges	10,875	9,531	30,442	27,114	40,040	36,988
Net income	$ 25,184	$ 22,981	$ 46,281	$ 38,936	$ 54,740	$ 46,863
Weighted average number of common shares outstanding - basic (in shares)	41,951	41,404	41,810	40,220	41,734	39,300
Weighted average number of common shares outstanding - diluted (in shares)	41,984	41,448	41,846	40,253	41,771	39,329
Total earnings per weighted average share of common stock - basic (in dollars per share)	$ 0.60	$ 0.56	$ 1.11	$ 0.97	$ 1.31	$ 1.19
Total earnings per weighted average share of common stock - diluted (in dollars per share)	$ 0.60	$ 0.55	$ 1.11	$ 0.97	$ 1.31	$ 1.19
Dividends per share of common stock (in dollars per share)	$ 0	$ 0.32	$ 0.64	$ 0.96	$ 0.96	$ 1.28