Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating revenues:
Electric, natural gas distribution and pipeline and energy services	$ 227,442	$ 204,455	$ 651,565	$ 599,533
Exploration and production, construction materials and contracting, construction services and other	833,153	763,507	1,340,633	1,221,236
Total operating revenues	1,060,595	967,962	1,992,198	1,820,769
Operating expenses:
Fuel and purchased power	18,169	15,193	39,777	33,613
Purchased natural gas sold	70,255	58,411	269,442	243,839
Operation and maintenance:
Electric, natural gas distribution and pipeline and energy services	76,627	52,717	142,730	121,115
Exploration and production, construction materials and contracting, construction services and other	661,495	623,347	1,055,511	999,497
Depreciation, depletion and amortization	95,289	83,627	188,850	169,007
Taxes, other than income	47,382	42,953	99,979	90,928
Total operating expenses	969,217	876,248	1,796,289	1,657,999
Operating income	91,378	91,714	195,909	162,770
Earnings (loss) from equity method investments	(7)	385	(319)	1,637
Other income	1,436	1,249	2,677	2,349
Interest expense	21,427	17,650	42,300	37,089
Income before income taxes	71,380	75,698	155,967	129,667
Income taxes	24,988	26,691	52,983	44,769
Income from continuing operations	46,392	49,007	102,984	84,898
Income (loss) from discontinued operations, net of tax	(59)	5,106	(136)	5,006
Net income	46,333	54,113	102,848	89,904
Net loss attributable to noncontrolling interest	(179)	0	(179)	0
Dividends declared on preferred stocks	171	171	342	343
Earnings on common stock	$ 46,341	$ 53,942	$ 102,685	$ 89,561
Earnings per common share - basic:
Earnings before discontinued operations	$ 0.25	$ 0.26	$ 0.54	$ 0.45
Discontinued operations, net of tax	$ 0.00	$ 0.03	$ 0.00	$ 0.02
Earnings per common share - basic	$ 0.25	$ 0.29	$ 0.54	$ 0.47
Earnings per common share - diluted:
Earnings before discontinued operations	$ 0.24	$ 0.26	$ 0.54	$ 0.45
Discontinued operations, net of tax	$ 0.00	$ 0.03	$ 0.00	$ 0.02
Earnings per common share - diluted	$ 0.24	$ 0.29	$ 0.54	$ 0.47
Dividends declared per common share	$ 0.1725	$ 0.1675	$ 0.3450	$ 0.3350
Weighted average common shares outstanding - basic	188,831	188,831	188,831	188,821
Weighted average common shares outstanding - diluted	189,463	189,107	189,460	189,096