Revenue from Contract with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
WRAM under-collection (alternative revenue program)	$ (88,140)	$ (76,733)	$ (152,863)	$ (141,145)
BRRAM over-collection (alternative revenue program)	(7,408)	(7,841)	(18,037)	(17,673)
Total operating revenues	124,647	106,901	226,380	201,629
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under-collection (alternative revenue program)	(88,140)	(76,733)	(152,863)	(141,145)
BRRAM over-collection (alternative revenue program)	(7,408)	(7,841)	(18,037)	(17,673)
Total operating revenues	95,548	84,574	170,900	158,818
Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	78,100	71,432	138,425	138,442
Regulated Operating Revenue	10,040
Total operating revenues	88,140	76,733	152,863	141,145
Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	7,741	7,858	19,061	17,924
BRRAM over-collection (alternative revenue program)	(333)	(17)	(1,024)	(251)
Total operating revenues	7,408	7,841	18,037	17,673
Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	29,099	22,327	55,480	42,811
Tariff-based Revenues \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	76,876	70,251	136,451	136,026
Tariff-based Revenues \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	7,698	7,795	18,964	17,814
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	763	728	1,054	1,521
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	43	63	97	110
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	461	453	920	895
Alternative revenues program [Member] \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under-collection (alternative revenue program)		(5,301)	(14,438)	(2,703)
Water \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	14,620	14,233	27,975	27,233
Wastewater \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 14,479	$ 8,094	$ 27,505	$ 15,578
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			85.00%

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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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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