Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Operating revenues	$ 342,713	$ 319,929	$ 809,343	$ 795,271
Fuel, purchased supply and direct transmission expense (exclusive of depreciation and depletion shown separately below)	75,271	76,480	213,468	251,201
Utilities Operating Expense, Maintenance and Operations	62,336	57,367	119,045	111,549
Administrative and general	33,773	31,281	75,130	71,726
Property and other taxes	48,168	36,256	91,408	83,427
Depreciation and depletion	62,379	56,933	124,779	113,676
Interest expense, net	(36,254)	(31,875)	(72,765)	(62,854)
Other income, net	78	6,160	4,006	10,479
Income tax expense	(3,382)	(4,243)	(18,586)	(14,577)
Net Income	21,228	31,654	98,168	96,740
Operating Segments | Electricity, US Regulated
Segment Reporting Information [Line Items]
Operating revenues	279,468	260,134	614,951	603,320
Fuel, purchased supply and direct transmission expense (exclusive of depreciation and depletion shown separately below)	59,603	60,887	152,355	176,228
Operating, general, and administrative	73,615	66,761	146,094	134,979
Property and other taxes	37,318	28,006	70,604	64,306
Depreciation and depletion	52,387	47,546	104,875	94,850
Interest expense, net	(27,562)	(23,298)	(55,318)	(47,955)
Other income, net	121	4,031	2,611	9,492
Income tax expense	(4,230)	(3,891)	(14,102)	(11,174)
Net Income	24,874	33,776	74,214	83,320
Operating Segments | Natural Gas, US Regulated
Segment Reporting Information [Line Items]
Operating revenues	63,245	59,795	194,392	191,951
Fuel, purchased supply and direct transmission expense (exclusive of depreciation and depletion shown separately below)	15,668	15,593	61,113	74,973
Operating, general, and administrative	22,773	21,721	47,943	45,650
Property and other taxes	10,850	8,251	20,645	19,120
Depreciation and depletion	9,992	9,387	19,904	18,826
Interest expense, net	(7,297)	(7,147)	(14,331)	(13,396)
Other income, net	456	927	1,547	1,981
Income tax expense	201	304	(4,226)	(2,869)
Net Income	(2,678)	(1,073)	27,777	19,098
Operating Segments | Regulated Electric and Natural Gas Segments
Segment Reporting Information [Line Items]
Operating revenues	342,713	319,929	809,343	795,271
Fuel, purchased supply and direct transmission expense (exclusive of depreciation and depletion shown separately below)	75,271	76,480	213,468	251,201
Operating, general, and administrative	96,388	88,482	194,037	180,629
Property and other taxes	48,168	36,257	91,249	83,426
Depreciation and depletion	62,379	56,933	124,779	113,676
Interest expense, net	(34,859)	(30,445)	(69,649)	(61,351)
Other income, net	577	4,958	4,158	11,473
Income tax expense	(4,029)	(3,587)	(18,328)	(14,043)
Net Income	22,196	32,703	101,991	102,418
Other Operating Segment | Operating Segments
Segment Reporting Information [Line Items]
Net Income	$ (968)	$ (1,049)	$ (3,823)	$ (5,678)