Revenues - Schedule of Disaggregated of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 181,290	$ 163,066	$ 350,481	$ 311,079
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Total operating revenues	131,050	119,697	244,160	221,700
Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	130,660	119,685	242,887	221,432
Total operating revenues	131,050	119,697	244,160	221,700
Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	13,440	13,164	32,835	26,940
Total operating revenues	13,626	12,928	32,283	27,930
Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	36,614	30,441	74,038	61,449
Tariff-based revenues | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	129,779	117,240	240,974	217,571
Tariff-based revenues | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	12,462	11,780	30,198	25,513
CPUC-approved surcharges (cost-recovery activities) | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	190	1,756	604	2,561
CPUC-approved surcharges (cost-recovery activities) | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	978	1,384	2,637	1,427
Other | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	691	689	1,309	1,300
Alternative revenues program | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	390	12	1,273	268
Alternative revenues program | Electric: | BVES
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	186	(236)	(552)	990
Water | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	23,714	14,398	46,892	31,010
Wastewater | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 12,900	$ 16,043	$ 27,146	$ 30,439