Bank Borrowings and Long-Term Liabilities - Borrowing Credit Agreement (Details) - Revolving Credit Facility - Credit Agreement - Line of Credit	Aug. 02, 2022 USD ($)
Line of Credit Facility [Line Items]
Initial Sublimit	$ 300,000,000
SJW Group
Line of Credit Facility [Line Items]
Initial Sublimit	50,000,000
SJWC
Line of Credit Facility [Line Items]
Initial Sublimit	140,000,000
CTWS
Line of Credit Facility [Line Items]
Initial Sublimit	90,000,000
SJWTX, Inc.
Line of Credit Facility [Line Items]
Initial Sublimit	$ 20,000,000

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant