Consolidated Statements of Income (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating revenues:
Gross operating revenues	$ 161,197	$ 162,365	$ 484,285	$ 448,894
Less: Cost of sales	90,122	86,301	270,747	234,862
Revenue taxes	3,843	3,871	11,798	10,913
Net operating revenues	67,232	72,193	201,740	203,119
Operating expenses:
Operations and maintenance	30,374	28,406	61,546	59,072
General taxes	6,659	7,543	14,824	10,792
Depreciation and amortization	17,546	16,026	34,855	31,927
Total operating expenses	54,579	51,975	111,225	101,791
Income from operations	12,653	20,218	90,515	101,328
Other income and expense - net	1,122	1,613	2,336	4,636
Interest expense - net	10,266	10,617	20,715	21,106
Income before income taxes	3,509	11,214	72,136	84,858
Income tax expense	1,316	4,326	29,170	34,362
Net income	$ 2,193	$ 6,888	$ 42,966	$ 50,496
Average common shares outstanding:
Basic	26,673	26,569	26,671	26,553
Diluted	26,727	26,641	26,725	26,621
Earnings per share of common stock:
Earnings per share of common stock - basic	$ 0.08	$ 0.26	$ 1.61	$ 1.90
Earnings per share of common stock - diluted	$ 0.08	$ 0.26	$ 1.61	$ 1.90
Dividends declared per share of common stock	$ 0.435	$ 0.415	$ 0.870	$ 0.830