Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating revenues:
Electric, natural gas distribution and pipeline and energy services	$ 192,103	$ 184,863	$ 843,670	$ 784,399
Exploration and production, construction materials and contracting, construction services and other	1,093,679	988,655	2,434,310	2,209,889
Total operating revenues	1,285,782	1,173,518	3,277,980	2,994,288
Operating expenses:
Fuel and purchased power	19,983	17,634	59,760	51,247
Purchased natural gas sold	35,826	35,199	305,268	279,038
Operation and maintenance:
Electric, natural gas distribution and pipeline and energy services	64,078	67,830	206,808	188,945
Exploration and production, construction materials and contracting, construction services and other	870,252	793,850	1,925,762	1,793,347
Depreciation, depletion and amortization	99,966	91,850	288,816	260,858
Taxes, other than income	45,804	41,090	145,784	132,017
Write-down of oil and natural gas properties (Note 5)	0	160,100	0	160,100
Total operating expenses	1,135,909	1,207,553	2,932,198	2,865,552
Operating income (loss)	149,873	(34,035)	345,782	128,736
Earnings (loss) from equity method investments	(61)	2,388	(380)	4,025
Other income	2,326	1,702	5,003	4,050
Interest expense	21,012	19,840	63,312	56,929
Income (loss) before income taxes	131,126	(49,785)	287,093	79,882
Income taxes	46,576	(20,253)	99,559	24,516
Income (loss) from continuing operations	84,550	(29,532)	187,534	55,366
Income (loss) from discontinued operations, net of tax (Note 11)	(118)	(139)	(254)	4,867
Net income (loss)	84,432	(29,671)	187,280	60,233
Net loss attributable to noncontrolling interest	(24)	0	(204)	0
Dividends declared on preferred stocks	171	171	514	514
Earnings (loss) on common stock	$ 84,285	$ (29,842)	$ 186,970	$ 59,719
Earnings (loss) per common share -- basic:
Earnings (loss) before discontinued operations	$ 0.45	$ (0.16)	$ 0.99	$ 0.29
Discontinued operations, net of tax	$ 0.00	$ 0.00	$ 0.00	$ 0.03
Earnings (loss) per common share -- basic	$ 0.45	$ (0.16)	$ 0.99	$ 0.32
Earnings (loss) per common share -- diluted:
Earnings (loss) before discontinued operations	$ 0.44	$ (0.16)	$ 0.99	$ 0.29
Discontinued operations, net of tax	$ 0.00	$ 0.00	$ 0.00	$ 0.03
Earnings (loss) per common share -- diluted	$ 0.44	$ (0.16)	$ 0.99	$ 0.32
Dividends declared per common share	$ 0.1725	$ 0.1675	$ 0.5175	$ 0.5025
Weighted average common shares outstanding - basic	188,831	188,831	188,831	188,824
Weighted average common shares outstanding - diluted	189,638	188,831	189,634	189,029