Revenue from Contracts with Customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 1,752,995	$ 1,805,807	$ 1,754,158
Other revenues	4,983	(2,455)	(6,860)
Total external operating revenues	1,757,978	1,803,352	1,747,298
Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	1,827,402	1,866,324	1,806,456
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(69,619)	(63,091)	(59,244)
Total external operating revenues	(69,619)	(63,091)	(59,244)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	235,268	197,762	178,176
Natural gas storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	23,690	18,254	14,583
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	113,325	83,642	70,761
Residential utility sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	786,103	860,874	856,825
Commercial utility sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	570,847	612,828	599,984
Industrial utility sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	85,471	88,268	85,476
Other utility sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,910	7,270	7,597
Electric | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	421,823	411,298	381,729
Other revenues	(7,417)	(10,261)	(4,714)
Total external operating revenues	414,406	401,037	377,015
Electric | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(72)	(138)	(58)
Total external operating revenues	(72)	(138)	(58)
Electric | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Electric | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Electric | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	59,288	54,508	45,608
Electric | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	140,054	136,274	138,634
Electric | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	171,760	170,321	146,182
Electric | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	42,883	43,063	43,766
Electric | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,910	7,270	7,597
Natural gas distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,188,942	1,279,617	1,275,990
Other revenues	12,033	7,619	(2,402)
Total external operating revenues	1,200,975	1,287,236	1,273,588
Natural gas distribution | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(130)	(301)	(216)
Total external operating revenues	(130)	(301)	(216)
Natural gas distribution | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	60,645	52,465	48,886
Natural gas distribution | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Natural gas distribution | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	40,703	15,141	13,617
Natural gas distribution | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	646,049	724,600	718,191
Natural gas distribution | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	399,087	442,507	453,802
Natural gas distribution | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	42,588	45,205	41,710
Natural gas distribution | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Pipeline | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	142,230	114,892	96,439
Other revenues	367	187	256
Total external operating revenues	142,597	115,079	96,695
Pipeline | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(69,222)	(62,533)	(58,884)
Total external operating revenues	(69,222)	(62,533)	(58,884)
Pipeline | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	174,623	145,297	129,290
Pipeline | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	23,690	18,254	14,583
Pipeline | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	13,139	13,874	11,450
Pipeline | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Pipeline | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Pipeline | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Pipeline | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other revenues	0	0	0
Total external operating revenues	0	0	0
Other | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(195)	(119)	(86)
Total external operating revenues	(195)	(119)	(86)
Other | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	195	119	86
Other | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0
Other | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 0	$ 0	$ 0