Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating revenues:
Operating revenues:	$ 1,000,795	$ 1,002,487	$ 3,522,020	$ 3,119,351
Operating expenses:
Operation and maintenance:	738,658	767,451	2,304,796	2,077,524
Purchased natural gas sold	55,967	61,863	542,848	444,527
Depreciation, depletion and amortization	53,146	51,843	158,877	158,622
Taxes, other than income	39,454	40,248	156,587	139,305
Electric fuel and purchased power	28,966	20,080	73,755	68,370
Total operating expenses	916,191	941,485	3,236,863	2,888,348
Operating income	84,604	61,002	285,157	231,003
Unrealized Gain (Loss) on investment in Knife River	30,150	0	170,170	0
Other income	8,918	5,774	29,251	2,521
Interest expense	32,129	20,196	82,541	58,275
Income before income taxes	91,543	46,580	402,037	175,249
Income taxes	13,325	4,211	92,311	28,352
Income from continuing operations	78,218	42,369	309,726	146,897
Discontinued operations, net of tax	(3,289)	105,602	(65,752)	103,504
Net income	$ 74,929	$ 147,971	$ 243,974	$ 250,401
Earnings per share - basic:
Income from continuing operations	$ 0.38	$ 0.21	$ 1.52	$ 0.72
Discontinued operations, net of tax	(0.01)	0.52	(0.32)	0.51
Earnings per share - basic	0.37	0.73	1.20	1.23
Earnings per share - diluted:
Income from continuing operations	0.38	0.21	1.52	0.72
Discontinued operations, net of tax	(0.01)	0.52	(0.32)	0.51
Earnings per share - diluted	$ 0.37	$ 0.73	$ 1.20	$ 1.23
Weighted average common shares outstanding - basic	203,638	203,351	203,633	203,351
Weighted average common shares outstanding - diluted	203,886	203,644	203,891	203,407
Regulated operation
Operating revenues:
Operating revenues:	$ 279,534	$ 263,774	$ 1,293,959	$ 1,141,007
Operating expenses:
Operation and maintenance:	99,295	89,662	296,818	281,909
Income from continuing operations	14,628	12,919	100,923	73,249
Nonregulated operation
Operating revenues:
Operating revenues:	721,261	738,713	2,228,061	1,978,344
Operating expenses:
Operation and maintenance:	639,363	677,789	2,007,978	1,795,615
Income from continuing operations	$ 63,590	$ 29,450	$ 208,803	$ 73,648