Consolidated Statements of 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:
Electric, natural gas distribution and pipeline and energy services	$ 204,455	$ 274,538	$ 599,533	$ 752,018
Exploration and production, construction materials and contracting, construction services and other	763,507	656,219	1,221,236	1,080,544
Total operating revenues	967,962	930,757	1,820,769	1,832,562
Operating expenses:
Fuel and purchased power	15,193	14,474	33,613	31,428
Purchased natural gas sold	58,411	101,538	243,839	346,224
Operation and maintenance:
Electric, natural gas distribution and pipeline and energy services	52,717	70,028	121,115	137,989
Exploration and production, construction materials and contracting, construction services and other	623,347	536,608	999,497	896,408
Depreciation, depletion and amortization	83,627	83,290	169,007	167,964
Taxes, other than income	42,953	42,516	90,928	92,181
Total operating expenses	876,248	848,454	1,657,999	1,672,194
Operating income (loss)	91,714	82,303	162,770	160,368
Earnings from equity method investments	385	949	1,637	1,433
Other income	1,249	1,908	2,349	3,809
Interest expense	17,650	20,036	37,089	42,053
Income (loss) before income taxes	75,698	65,124	129,667	123,557
Income taxes	26,691	19,889	44,769	35,793
Income (loss) from continuing operations	49,007	45,235	84,898	87,764
Income (loss) from discontinued operations, net of tax	5,106	(168)	5,006	280
Net income (loss)	54,113	45,067	89,904	88,044
Dividends declared on preferred stocks	171	171	343	342
Earnings (loss) on common stock	$ 53,942	$ 44,896	$ 89,561	$ 87,702
Earnings (loss) per common share - basic:
Earnings (loss) before discontinued operations	$ 0.26	$ 0.24	$ 0.45	$ 0.46
Discontinued operations, net of tax	$ 0.03	$ 0.00	$ 0.02	$ 0.00
Earnings (loss) per common share - basic	$ 0.29	$ 0.24	$ 0.47	$ 0.46
Earnings (loss) per common share - diluted:
Earnings (loss) before discontinued operations	$ 0.26	$ 0.24	$ 0.45	$ 0.46
Discontinued operations, net of tax	$ 0.03	$ 0.00	$ 0.02	$ 0.00
Earnings (loss) per common share - diluted	$ 0.29	$ 0.24	$ 0.47	$ 0.46
Dividends declared per common share (in dollars per share)	$ 0.1675	$ 0.1625	$ 0.3350	$ 0.3250
Weighted average common shares outstanding - basic	188,831	188,794	188,821	188,732
Weighted average common shares outstanding - diluted	189,107	188,968	189,096	188,903