Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 135,251	$ 161,423
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Total operating revenues	90,265	112,712
Water:
Disaggregation of Revenue [Line Items]
Retroactive water revenues impact as a result of a proposed decision		30,000
Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	85,790	101,595
Total operating revenues	90,265	112,712
Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	12,747	13,212
Total operating revenues	12,205	12,904
Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	32,781	35,807
Tariff-based revenues | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	84,661	100,541
Tariff-based revenues | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	12,673	13,063
CPUC-approved surcharges (cost-recovery activities) | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	547	317
CPUC-approved surcharges (cost-recovery activities) | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	74	149
Other | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	582	737
WRAM under/(over)-collection (alternative revenue program) | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	4,475	11,117
WRAM under/(over)-collection (alternative revenue program) | Electric: | BVES
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	(542)	(308)
Water | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	21,567	22,488
Wastewater | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 11,214	$ 13,319