Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating revenues:
Operating revenues:	$ 1,563,799	$ 1,280,787	$ 3,958,563	$ 3,321,678
Operating expenses:
Operation and maintenance:	1,212,620	996,591	2,936,564	2,419,531
Purchased natural gas sold	31,843	32,123	270,539	270,319
Depreciation, depletion and amortization	65,021	55,016	187,937	161,298
Taxes, other than income	46,128	38,647	148,110	128,257
Electric fuel and purchased power	18,717	18,406	64,413	58,901
Total operating expenses	1,374,329	1,140,783	3,607,563	3,038,306
Operating income	189,470	140,004	351,000	283,372
Other income	3,014	2,683	12,222	4,864
Interest expense	25,258	20,955	74,094	62,202
Income before income taxes	167,226	121,732	289,128	226,034
Income taxes	31,098	14,363	48,766	32,629
Income from continuing operations	136,128	107,369	240,362	193,405
Income (loss) from discontinued operations, net of tax (Note 10)	1,509	(118)	26	85
Net income	$ 137,637	$ 107,251	$ 240,388	$ 193,490
Earnings per share - basic:
Income from continuing operations	$ 0.68	$ 0.55	$ 1.21	$ 0.99
Discontinued operations, net of tax	0.01	0	0	0
Earnings per share - basic	0.69	0.55	1.21	0.99
Earnings per share - diluted:
Income from continuing operations	0.68	0.55	1.21	0.99
Discontinued operations, net of tax	0.01	0	0	0
Earnings per share - diluted	$ 0.69	$ 0.55	$ 1.21	$ 0.99
Weighted average common shares outstanding - basic	199,343	196,018	198,016	195,618
Weighted average common shares outstanding - diluted	199,383	196,265	198,033	196,104
Regulated operation
Operating revenues:
Operating revenues:	$ 209,444	$ 200,617	$ 885,309	$ 851,761
Operating expenses:
Operation and maintenance:	86,249	82,920	262,434	252,961
Income from continuing operations	7,599	13,506	74,206	72,193
Nonregulated operation
Operating revenues:
Operating revenues:	1,354,355	1,080,170	3,073,254	2,469,917
Operating expenses:
Operation and maintenance:	1,126,371	913,671	2,674,130	2,166,570
Income from continuing operations	$ 128,529	$ 93,863	$ 166,156	$ 121,212