XML 98 R79.htm IDEA: XBRL DOCUMENT
v3.20.4

Financial Statement Schedule - Additional Information (Details) $ in Thousands | Dec. 31, 2020 USD ($)
--- | ---
Condensed Financial Information Disclosure [Abstract] |
Restricted net assets, subsidiaries | $ 283,807
Restricted net assets, subsidiaries, percent of consolidated assets | 31.00%

X
- Definition Restricted Net Assets, Subsidiaries + References No definition available. + Details
Name: | sjw_RestrictedNetAssetsSubsidiaries
Namespace Prefix: | sjw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Restricted Net Assets, Subsidiaries, Percent Of Consolidated Assets + References No definition available. + Details
Name: | sjw_RestrictedNetAssetsSubsidiariesPercentOfConsolidatedAssets
Namespace Prefix: | sjw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | srt_CondensedFinancialInformationOfParentCompanyOnlyDisclosureAbstract
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration