Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating revenues:
Electric, natural gas distribution and regulated pipeline and midstream	$ 192,079	$ 185,417	$ 783,997	$ 807,585
Nonregulated pipeline and midstream, construction materials and contracting, construction services and other	1,016,488	1,012,925	2,328,733	2,189,640
Total operating revenues	1,208,567	1,198,342	3,112,730	2,997,225
Operating expenses:
Fuel and purchased power	16,800	20,616	54,725	63,761
Purchased natural gas sold	34,321	37,574	242,795	305,313
Operation and maintenance:
Electric, natural gas distribution and regulated pipeline and midstream	77,662	68,344	229,364	207,144
Nonregulated pipeline and midstream, construction materials and contracting, construction services and other	842,878	859,843	2,008,122	1,919,455
Depreciation, depletion and amortization	54,094	51,746	163,226	154,669
Taxes, other than income	36,128	32,391	116,864	109,039
Total operating expenses	1,061,883	1,070,514	2,815,096	2,759,381
Operating income	146,684	127,828	297,634	237,844
Other income	1,741	3,300	3,662	5,673
Interest expense	22,278	22,417	67,365	68,872
Income before income taxes	126,147	108,711	233,931	174,645
Income taxes	37,761	34,825	67,381	54,157
Income from continuing operations	88,386	73,886	166,550	120,488
Loss from discontinued operations, net of tax (Note 10)	(5,400)	(223,112)	(299,538)	(816,517)
Net income (loss)	82,986	(149,226)	(132,988)	(696,029)
Loss from discontinued operations attributable to noncontrolling interest (Note 10)	0	(9,778)	(131,691)	(21,060)
Dividends declared on preferred stocks	171	171	514	514
Earnings (loss) on common stock	$ 82,815	$ (139,619)	$ (1,811)	$ (675,483)
Earnings (loss) per common share - basic:
Earnings before discontinued operations	$ 0.45	$ 0.38	$ 0.85	$ 0.62
Discontinued operations attributable to the Company, net of tax	(0.03)	(1.10)	(0.86)	(4.09)
Earnings (loss) per common share - basic	0.42	(0.72)	(0.01)	(3.47)
Earnings (loss) per common share - diluted:
Earnings before discontinued operations	0.45	0.38	0.85	0.62
Discontinued operations attributable to the Company, net of tax	(0.03)	(1.10)	(0.86)	(4.09)
Earnings (loss) per common share - diluted	0.42	(0.72)	(0.01)	(3.47)
Dividends declared per common share	$ 0.1875	$ 0.1825	$ 0.5625	$ 0.5475
Weighted average common shares outstanding - basic	195,304	195,151	195,298	194,814
Weighted average common shares outstanding - diluted	195,811	195,169	195,794	194,833