Statements of Consolidated Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating revenues	$ 337,804	$ 367,791	$ 787,764	$ 840,486
Operating expenses:
Purchased gas costs	39,667	40,250	123,733	155,488
Operation and maintenance	34,815	30,586	69,205	55,641
Production	22,572	19,765	49,595	35,876
Exploration	1,887	1,198	3,715	2,573
Selling, general and administrative	41,778	40,936	84,720	79,827
Depreciation, depletion and amortization	115,681	81,886	223,206	160,284
Total operating expenses	256,400	214,621	554,174	489,689
Gain on dispositions			1,110	22,785
Operating income	81,404	153,170	234,700	373,582
Other income	5,249	18,046	9,930	24,850
Interest expense	40,629	33,287	81,881	66,139
Income before income taxes	46,024	137,929	162,749	332,293
Income taxes	14,578	50,175	59,268	122,284
Net income	$ 31,446	$ 87,754	$ 103,481	$ 210,009
Basic:
Weighted average common shares outstanding (in shares)	149,582	149,444	149,532	149,347
Net income (in dollars per share)	$ 0.21	$ 0.59	$ 0.69	$ 1.41
Diluted:
Weighted average common shares outstanding (in shares)	150,149	150,111	150,200	150,034
Net income (in dollars per share)	$ 0.21	$ 0.58	$ 0.69	$ 1.40
Dividends declared per common share (in dollars per share)	$ 0.22	$ 0.22	$ 0.44	$ 0.44