Revenue from Contract with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	$ 64,723	$ 64,412
Revenues	101,733	94,728
GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
WRAM under (over)-collection (alternative revenue program)	64,723	64,412
Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	60,325	67,010
WRAM under (over)-collection (alternative revenue program)	(4,398)	(2,598)
Revenues	64,723	64,412
Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	11,320	10,066
BRRAM over-collection (alternative revenue program)	691	(234)
Revenues	10,629	9,832
Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	26,381	20,484
Tariff-based Revenues \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	59,575	65,775
Tariff-based Revenues \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	11,266	10,019
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	291	793
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	54	47
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	459	442
Water \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	13,355	13,000
Wastewater \| Contracted Services \| ASUS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 13,026	$ 7,484
Sales \| Water Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	90.00%	90.00%
Sales \| Electric Service Utility Operations \| GOLDEN STATE WATER COMPANY
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	85.00%	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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
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-Section 50
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The amount of regulated power revenues recognized during the period.

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The amount of regulated water operating revenues recognized during the period.

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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