v3.26.1
Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets $ 92 $ 9,264
GSWC    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (41,788) (36,994)
GSWC | Deferred Income Tax Charge    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (63,152) (63,223)
GSWC | Pension Costs and Other Postretirement Benefit Costs    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (43,984) (43,479)
GSWC | PFAS Contamination Litigation Proceeds Memorandum Account    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (10,406) (10,987)
GSWC | Other regulatory liabilities    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (218) (1,331)
BVES    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 41,880 46,258
BVES | Other regulatory liabilities    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets (4,624) (4,015)
2022/2023 general rate case memorandum accounts (unbilled revenue) | GSWC    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 18,814 22,107
Flowed-through deferred income taxes, net | GSWC    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 22,286 20,932
Low income rate assistance balancing accounts | GSWC    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 11,502 10,582
Other regulatory assets | GSWC    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 23,370 28,405
Other regulatory assets | BVES    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 13,682 15,213
Derivative instrument memorandum account (Note 5) | BVES    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 15,708 15,503
2023/2024 General Rate Case Memorandum accounts ( unbilled revenue) | BVES    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets 7,237 8,221
Wildfire mitigation and other fire prevention related costs memorandum accounts | BVES    
Schedule of Regulatory Assets and Liabilities [Line Items]    
Net regulatory Assets $ 9,877 $ 11,336