Revenue from Contract with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	$ (95,249)	$ (87,689)	$ (248,112)	$ (228,834)
BRRAM under (over)-collection (alternative revenue program)	(11,996)	(7,875)	(30,033)	(25,548)
Total operating revenues	134,496	124,182	360,876	325,811
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	(95,249)	(87,689)	(248,112)	(228,834)
BRRAM under (over)-collection (alternative revenue program)	(11,996)	(7,875)	(30,033)	(25,548)
Total operating revenues	107,245	95,564	278,145	254,382
Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	91,505	88,627	229,930	227,069
Regulated Operating Revenue	3,744
Total operating revenues	95,249	87,689	248,112	228,834
Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	9,780	8,269	28,841	26,193
BRRAM under (over)-collection (alternative revenue program)	(2,216)	394	(1,192)	645
Total operating revenues	11,996	7,875	30,033	25,548
Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	27,251	28,618	82,731	71,429
Tariff-based Revenues \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	89,050	87,204	225,501	223,230
Tariff-based Revenues \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	9,729	8,207	28,693	26,021
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	1,900	937	2,954	2,458
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	51	62	148	172
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	555	486	1,475	1,381
Alternative revenues program [Member] \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)		938	(18,182)	(1,765)
Water \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	13,797	16,909	41,772	44,134
Wastewater \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 13,454	$ 11,709	$ 40,959	$ 27,295
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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