Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenues:
Electric, natural gas distribution and regulated pipeline and midstream	$ 433,614	$ 385,865
Nonregulated pipeline and midstream, construction materials and contracting, construction services and other	504,311	474,349
Total operating revenues	937,925	860,214
Operating expenses:
Fuel and purchased power	21,886	22,011
Purchased natural gas sold	192,948	161,035
Operation and maintenance:
Electric, natural gas distribution and regulated pipeline and midstream	78,738	74,625
Nonregulated pipeline and midstream, construction materials and contracting, construction services and other	478,478	442,500
Depreciation, depletion and amortization	51,325	54,884
Taxes, other than income	47,438	43,174
Total operating expenses	870,813	798,229
Operating income	67,112	61,985
Other income	1,017	1,049
Interest expense	20,303	22,868
Income before income taxes	47,826	40,166
Income taxes	12,188	8,301
Income from continuing operations	35,638	31,865
Income (loss) from discontinued operations, net of tax (Note 8)	1,687	(18,036)
Net income	37,325	13,829
Loss from discontinued operations attributable to noncontrolling interest (Note 8)	0	(11,040)
Dividends declared on preferred stocks	171	171
Earnings on common stock	$ 37,154	$ 24,698
Earnings per common share - basic:
Earnings before discontinued operations	$ 0.18	$ 0.16
Discontinued operations attributable to the Company, net of tax	0.01	(0.03)
Earnings per common share - basic	0.19	0.13
Earnings per common share - diluted:
Earnings before discontinued operations	0.18	0.16
Discontinued operations attributable to the Company, net of tax	0.01	(0.03)
Earnings per common share - diluted	0.19	0.13
Dividends declared per common share	$ 0.1925	$ 0.1875
Weighted average common shares outstanding - basic	195,304	195,284
Weighted average common shares outstanding - diluted	196,023	195,284