Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating revenues:
Operating revenues:	$ 1,587,289	$ 1,563,799	$ 4,147,591	$ 3,958,563
Operating expenses:
Operation and maintenance:	1,214,019	1,212,620	3,064,189	2,936,564
Purchased natural gas sold	31,524	31,843	253,780	270,539
Depreciation, depletion and amortization	72,084	65,021	212,832	187,937
Taxes, other than income	50,501	46,128	167,197	148,110
Electric fuel and purchased power	15,450	18,717	50,557	64,413
Total operating expenses	1,383,578	1,374,329	3,748,555	3,607,563
Operating income	203,711	189,470	399,036	351,000
Other income	4,612	3,014	13,669	12,222
Interest expense	23,761	25,258	73,132	74,094
Income before income taxes	184,562	167,226	339,573	289,128
Income taxes	31,547	31,098	61,178	48,766
Income from continuing operations	153,015	136,128	278,395	240,362
Income (loss) from discontinued operations, net of tax	63	1,509	(484)	26
Net income	$ 153,078	$ 137,637	$ 277,911	$ 240,388
Earnings per share - basic:
Income from continuing operations	$ 0.76	$ 0.68	$ 1.39	$ 1.21
Discontinued operations, net of tax	0	0.01	0	0
Earnings per share - basic	0.76	0.69	1.39	1.21
Earnings per share - diluted:
Income from continuing operations	0.76	0.68	1.39	1.21
Discontinued operations, net of tax	0	0.01	0	0
Earnings per share - diluted	$ 0.76	$ 0.69	$ 1.39	$ 1.21
Weighted average common shares outstanding - basic	200,522	199,343	200,495	198,016
Weighted average common shares outstanding - diluted	200,619	199,383	200,515	198,033
Regulated operation
Operating revenues:
Operating revenues:	$ 210,115	$ 209,444	$ 870,151	$ 885,309
Operating expenses:
Operation and maintenance:	89,080	86,249	259,791	262,434
Income from continuing operations	6,985	7,599	77,991	74,206
Nonregulated operation
Operating revenues:
Operating revenues:	1,377,174	1,354,355	3,277,440	3,073,254
Operating expenses:
Operation and maintenance:	1,124,939	1,126,371	2,804,398	2,674,130
Income from continuing operations	$ 146,030	$ 128,529	$ 200,404	$ 166,156