Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Income Statement [Abstract]
Operating revenues	$ 674,833	$ 588,275
Operating expenses:
Purchased natural gas sold	317,157	258,602
Electric fuel and purchased power	43,748	39,723
Operation and maintenance	111,047	107,614
Depreciation and amortization	51,261	49,767
Taxes, other than income	38,757	35,913
Total operating expenses	561,970	491,619
Operating income	112,863	96,656
Other income	4,997	11,909
Interest expense	26,822	26,511
Income before income taxes	91,038	82,054
Income taxes	8,571	7,319
Income from continuing operations	82,467	74,735
Discontinued operations, net of tax	(502)	26,163
Net income	$ 81,965	$ 100,898
Earnings per share - basic:
Income from continuing operations (in usd per share)	$ 0.40	$ 0.37
Discontinued operations, net of tax (in usd per share)	0	0.13
Earnings per share - basic (in usd per share)	0.40	0.50
Earnings per share - diluted:
Income from continuing operations (in usd per share)	0.40	0.37
Discontinued operations, net of tax (in usd per share)	0	0.12
Earnings per share - diluted (in usd per share)	$ 0.40	$ 0.49
Weighted average common shares outstanding - basic (in shares)	204,142	203,779
Weighted average common shares outstanding - diluted (in shares)	204,959	204,187