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Condensed Consolidating Financial Statements - Additional Information (Details) - USD ($) | Sep. 30, 2020 | Nov. 17, 2010
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Cal Water |  |
Debt Instrument [Line Items] |  |
Ownership interest (as a percent) | 100.00% |
All Other Subsidiaries |  |
Debt Instrument [Line Items] |  |
Ownership interest (as a percent) | 100.00% |
First Mortgage Bonds, 5.500% due 2040 | Cal Water |  |
Debt Instrument [Line Items] |  |
Debt issued |  | $ 100,000,000.0
Interest rate |  | 5.50%

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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