Revenue from Contract with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	$ (71,424)	$ (64,723)
BRRAM under (over)-collection (alternative revenue program)	(10,968)	(10,629)
Total operating revenues	109,077	101,733
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	(71,424)	(64,723)
BRRAM under (over)-collection (alternative revenue program)	(10,968)	(10,629)
Total operating revenues	82,392	75,352
Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	70,483	60,325
Regulated Operating Revenue	941
Total operating revenues	71,424	64,723
Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	10,290	11,320
BRRAM under (over)-collection (alternative revenue program)	(678)	691
Total operating revenues	10,968	10,629
Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	26,685	26,381
Tariff-based Revenues \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	69,254	59,575
Tariff-based Revenues \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	10,032	11,266
Surcharges (Cost-recovery Activities) \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	734	291
Surcharges (Cost-recovery Activities) \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	258	54
Other Products and Services \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	495	459
Alternative revenues program [Member] \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)		(4,398)
Water \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	14,701	13,355
Wastewater \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 11,984	$ 13,026
Sales \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	90.00%
Sales \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	90.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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