Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating revenues:
Electric, natural gas distribution and pipeline and energy services	$ 424,124	$ 395,081
Exploration and production, construction materials and contracting, construction services and other	507,480	457,726
Total operating revenues	931,604	852,807
Operating expenses:
Fuel and purchased power	21,608	18,420
Purchased natural gas sold	199,187	185,428
Operation and maintenance:
Electric, natural gas distribution and pipeline and energy services	66,101	68,401
Exploration and production, construction materials and contracting, construction services and other	394,019	376,146
Depreciation, depletion and amortization	93,561	85,380
Taxes, other than income	52,597	47,975
Total operating expenses	827,073	781,750
Operating income	104,531	71,057
Earnings (loss) from equity method investments	(311)	1,253
Other income	1,242	1,098
Interest expense	20,874	19,439
Income before income taxes	84,588	53,969
Income taxes	27,996	18,079
Income from continuing operations	56,592	35,890
Loss from discontinued operations, net of tax	(77)	(100)
Net income	56,515	35,790
Dividends declared on preferred stocks	171	171
Earnings on common stock	$ 56,344	$ 35,619
Earnings per common share - basic:
Earnings before discontinued operations	$ 0.30	$ 0.19
Discontinued operations, net of tax	$ 0.00	$ 0.00
Earnings per common share - basic	$ 0.30	$ 0.19
Earnings per common share - diluted:
Earnings before discontinued operations	$ 0.30	$ 0.19
Discontinued operations, net of tax	$ 0.00	$ 0.00
Earnings per common share - diluted	$ 0.30	$ 0.19
Dividends declared per common share	$ 0.1725	$ 0.1675
Weighted average common shares outstanding - basic	188,831	188,811
Weighted average common shares outstanding - diluted	189,222	189,182