Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Statement [Abstract]
Operating revenues	$ 315,036	$ 289,694	$ 1,341,055	$ 1,222,440
Operating expenses:
Purchased natural gas sold	58,514	53,377	471,728	406,569
Electric fuel and purchased power	41,098	32,576	119,737	108,991
Operation and maintenance	101,762	101,211	325,696	308,780
Depreciation and amortization	52,046	49,835	155,160	149,292
Taxes, other than income	21,776	17,849	85,699	77,731
Total operating expenses	275,196	254,848	1,158,020	1,051,363
Operating income	39,840	34,846	183,035	171,077
Other income	7,298	8,970	22,240	31,242
Interest expense	26,417	27,337	78,684	80,349
Income before income taxes	20,721	16,479	126,591	121,970
Income taxes	2,371	876	11,597	11,390
Income from continuing operations	18,350	15,603	114,994	110,580
Discontinued operations, net of tax	(39)	49,012	(938)	115,370
Net income	$ 18,311	$ 64,615	$ 114,056	$ 225,950
Earnings per share - basic:
Income from continuing operations (in usd per share)	$ 0.09	$ 0.08	$ 0.56	$ 0.54
Discontinued operations, net of tax (in usd per share)	0	0.24	0	0.57
Earnings per share - basic (in usd per share)	0.09	0.32	0.56	1.11
Earnings per share - diluted:
Income from continuing operations (in usd per share)	0.09	0.08	0.56	0.54
Discontinued operations, net of tax (in usd per share)	0	0.24	0	0.57
Earnings per share - diluted (in usd per share)	$ 0.09	$ 0.32	$ 0.56	$ 1.11
Weighted average common shares outstanding - basic (in shares)	204,331	203,888	204,269	203,852
Weighted average common shares outstanding - diluted (in shares)	205,285	204,678	205,153	204,451