Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating revenues:
Operating revenues:	$ 1,047,545	$ 1,091,126	$ 2,261,370	$ 2,521,224
Operating expenses:
Total operation and maintenance	732,992	769,593	1,404,910	1,566,138
Purchased natural gas sold	94,591	115,866	353,192	486,881
Electric fuel and purchased power	29,716	20,432	62,333	44,789
Depreciation and amortization	55,882	53,498	111,631	105,730
Taxes, other than income	44,618	49,706	103,611	117,133
Total operating expenses	957,799	1,009,095	2,035,677	2,320,671
Operating income	89,746	82,031	225,693	200,553
Unrealized gain on retained shares in Knife River	0	140,020	0	140,020
Other income	14,662	9,959	28,449	20,333
Interest expense	28,609	26,459	57,314	50,412
Income before income taxes	75,799	205,551	196,828	310,494
Income taxes	15,225	57,918	35,356	78,986
Income from continuing operations	60,574	147,633	161,472	231,508
Discontinued operations, net of tax	(138)	(16,941)	(138)	(62,464)
Net income	$ 60,436	$ 130,692	$ 161,334	$ 169,044
Earnings per share - basic:
Income from continuing operations (in usd per share)	$ 0.30	$ 0.72	$ 0.79	$ 1.14
Discontinued operations, net of tax (in usd per share)	0	(0.08)	0	(0.31)
Earnings per share - basic (in usd per share)	0.30	0.64	0.79	0.83
Earnings per share - diluted:
Income from continuing operations (in usd per share)	0.30	0.72	0.79	1.14
Discontinued operations, net of tax (in usd per share)	0	(0.08)	0	(0.31)
Earnings per share - diluted (in usd per share)	$ 0.30	$ 0.64	$ 0.79	$ 0.83
Weighted average common shares outstanding - basic (in shares)	203,888	203,635	203,834	203,630
Weighted average common shares outstanding - diluted (in shares)	204,582	203,877	204,364	203,894
Regulated operation
Operating revenues:
Operating revenues:	$ 340,544	$ 340,492	$ 926,561	$ 1,014,423
Operating expenses:
Total operation and maintenance	100,709	95,483	206,389	197,522
Income from continuing operations	27,360	21,832	100,703	86,296
Nonregulated operation
Operating revenues:
Operating revenues:	707,001	750,634	1,334,809	1,506,801
Operating expenses:
Total operation and maintenance	632,283	674,110	1,198,521	1,368,616
Income from continuing operations	$ 33,214	$ 125,801	$ 60,769	$ 145,212