Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating revenues:
Operating revenues:	$ 1,586,013	$ 1,587,289	$ 4,237,608	$ 4,147,591
Operating expenses:
Operation and maintenance:	1,212,898	1,214,019	3,102,353	3,064,189
Purchased natural gas sold	41,135	31,524	280,584	253,780
Depreciation, depletion and amortization	75,229	72,084	222,613	212,832
Taxes, other than income	48,096	50,501	163,819	167,197
Electric fuel and purchased power	19,486	15,450	56,216	50,557
Total operating expenses	1,396,844	1,383,578	3,825,585	3,748,555
Operating income	189,169	203,711	412,023	399,036
Other income	5,930	4,612	18,310	13,669
Interest expense	23,389	23,761	70,224	73,132
Income before income taxes	171,710	184,562	360,109	339,573
Income taxes	32,748	31,547	68,860	61,178
Income from continuing operations	138,962	153,015	291,249	278,395
Income (loss) from discontinued operations, net of tax	314	63	348	(484)
Net income	$ 139,276	$ 153,078	$ 291,597	$ 277,911
Earnings per share - basic:
Income from continuing operations	$ 0.68	$ 0.76	$ 1.44	$ 1.39
Discontinued operations, net of tax	0	0	0	0
Earnings per share - basic	0.68	0.76	1.44	1.39
Earnings per share - diluted:
Income from continuing operations	0.68	0.76	1.44	1.39
Discontinued operations, net of tax	0	0	0	0
Earnings per share - diluted	$ 0.68	$ 0.76	$ 1.44	$ 1.39
Weighted average common shares outstanding - basic	202,863	200,522	201,647	200,495
Weighted average common shares outstanding - diluted	203,190	200,619	201,955	200,515
Regulated operation
Operating revenues:
Operating revenues:	$ 237,065	$ 210,115	$ 940,017	$ 870,151
Operating expenses:
Operation and maintenance:	90,058	89,080	273,796	259,791
Income from continuing operations	15,399	6,985	89,207	77,991
Nonregulated operation
Operating revenues:
Operating revenues:	1,348,948	1,377,174	3,297,591	3,277,440
Operating expenses:
Operation and maintenance:	1,122,840	1,124,939	2,828,557	2,804,398
Income from continuing operations	$ 123,563	$ 146,030	$ 202,042	$ 200,404