Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 157,400	$ 122,607	$ 318,823	$ 231,177
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Total operating revenues	116,908	90,856	229,620	164,762
Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	99,585	84,980	201,180	158,545
Total operating revenues	116,908	90,856	229,620	164,762
Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	9,046	8,413	22,258	20,992
Total operating revenues	8,828	8,217	21,732	20,109
Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	31,664	23,534	67,471	46,306
Tariff-based revenues | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	98,378	83,612	198,919	156,110
Tariff-based revenues | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	8,929	8,381	21,992	20,933
Surcharges (cost-recovery activities) | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	558	797	875	1,346
Surcharges (cost-recovery activities) | Electric: | BVES
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	117	32	266	59
Other | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	649	571	1,386	1,089
WRAM under-collection (alternative revenue program) | Water: | GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	17,323	5,876	28,440	6,217
WRAM under-collection (alternative revenue program) | Electric: | BVES
Disaggregation of Revenue [Line Items]
Alternative revenue programs, net	(218)	(196)	(526)	(883)
Water | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	19,181	14,175	41,669	27,721
Wastewater | Contracted services: | ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 12,483	$ 9,359	$ 25,802	$ 18,585