CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating revenues:
Electric and water	$ 124,091	$ 120,329	$ 243,817	$ 248,690	$ 519,403	$ 512,686
Gas	5,804	7,303	21,487	28,292	39,625	48,101
Other	1,737	1,461	3,472	2,839	6,797	5,934
Total operating revenues	131,632	129,093	268,776	279,821	565,825	566,721
Operating revenue deductions:
Fuel and purchased power	45,528	47,228	90,757	101,445	189,568	205,805
Cost of natural gas sold and transported	1,769	2,712	10,350	14,752	18,359	23,991
Regulated operating expenses	22,844	19,085	46,192	38,801	92,834	79,904
Other operating expenses	771	649	1,369	1,123	2,493	2,106
Maintenance and repairs	10,797	10,540	19,920	19,782	41,180	39,146
Depreciation and amortization	15,068	16,888	30,003	34,221	59,318	66,106
Provision for income taxes	6,673	5,588	12,757	12,857	33,971	28,999
Other taxes	7,420	7,269	15,855	15,859	30,577	29,545
Total operating revenue deductions	110,870	109,959	227,203	238,840	468,300	475,602
Operating income	20,762	19,134	41,573	40,981	97,525	91,119
Other income and (deductions):
Allowance for equity funds used during construction	53	70	103	70	326	954
Interest income	123	16	302	40	819	94
Benefit/(provision) for other income taxes	(87)	9	(202)	33	(462)	61
Other - non-operating expense, net	(202)	(174)	(429)	(460)	(1,252)	(996)
Total other income and (deductions)	(113)	(79)	(226)	(317)	(569)	113
Interest charges:
Long-term debt	9,637	10,640	20,292	21,273	41,599	42,664
Short-term debt	129	16	159	47	199	188
Allowance for borrowed funds used during construction	(118)	(58)	(167)	(81)	(304)	(872)
Other	293	(718)	551	(1,672)	1,075	(3,285)
Total interest charges	9,941	9,880	20,835	19,567	42,569	38,695
Net income	$ 10,708	$ 9,175	$ 20,512	$ 21,097	$ 54,387	$ 52,537
Weighted average number of common shares outstanding - basic (in shares)	42,197	41,811	42,122	41,738	42,042	41,596
Weighted average number of common shares outstanding - diluted (in shares)	42,220	41,846	42,143	41,774	42,061	41,627
Total earnings per weighted average share of common stock - basic and diluted (in dollars per share)	$ 0.25	$ 0.22	$ 0.49	$ 0.51	$ 1.29	$ 1.26
Dividends declared per share of common stock (in dollars per share)	$ 0.25	$ 0.32	$ 0.50	$ 0.64	$ 0.50	$ 1.28