Revenues - Schedule of Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Net asset optimization gain (expense)	$ 3,661	$ (2,249)
Total Revenues	159,029	142,257
Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	155,368	144,503
Other revenue
Disaggregation of Revenue [Line Items]
Retail revenues	0	3
POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	97,661	84,900
Non-POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	57,707	59,603
Unbilled revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	27,307	(6,064)
Commercial \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	39,114	45,847
Residential \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	88,947	104,720
New England \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	30,322	26,467
Mid-Atlantic \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	69,095	59,084
Midwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	22,494	20,338
Southwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	33,457	38,614
Retail Electricity \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	86,866	80,720
Retail Electricity \| POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	63,134	55,934
Retail Electricity \| Non-POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	23,732	24,786
Retail Electricity \| Unbilled revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	13,195	(6,298)
Retail Electricity \| Commercial \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	8,872	10,801
Retail Electricity \| Residential \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	64,799	76,217
Retail Electricity \| New England \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	20,352	21,272
Retail Electricity \| Mid-Atlantic \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	46,306	38,860
Retail Electricity \| Midwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	8,551	8,119
Retail Electricity \| Southwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	11,657	12,469
Retail Natural Gas \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	68,502	63,783
Retail Natural Gas \| POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	34,527	28,966
Retail Natural Gas \| Non-POR \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	33,975	34,817
Retail Natural Gas \| Unbilled revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	14,112	234
Retail Natural Gas \| Commercial \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	30,242	35,046
Retail Natural Gas \| Residential \| Billed Revenue \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	24,148	28,503
Retail Natural Gas \| New England \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	9,970	5,195
Retail Natural Gas \| Mid-Atlantic \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	22,789	20,224
Retail Natural Gas \| Midwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	13,943	12,219
Retail Natural Gas \| Southwest \| Retail revenues
Disaggregation of Revenue [Line Items]
Retail revenues	$ 21,800	$ 26,145