Long-Term Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total debt	$ 1,583,441	$ 1,488,788
Unamortized debt premium and discount, net	1,583	17,396
Unamortized debt issuance costs	(9,350)	(9,859)
Current portion	(48,975)	(4,360)
Total long-term debt, less current portion	1,526,699	1,491,965
SJW Group
Debt Instrument [Line Items]
Total long-term debt, less current portion	557,028	556,627
SJW Group \| Senior notes
Debt Instrument [Line Items]
Total debt	$ 560,000	560,000
SJW Group \| Senior notes \| Minimum
Debt Instrument [Line Items]
Rate	2.47%
SJW Group \| Senior notes \| Maximum
Debt Instrument [Line Items]
Rate	3.53%
SJWC \| California Pollution Control Financing Authority Revenue Bond
Debt Instrument [Line Items]
Total debt	$ 540,000	470,000
SJWC \| Senior notes
Debt Instrument [Line Items]
Total debt	$ 470,000	400,000
SJWC \| Senior notes \| Minimum
Debt Instrument [Line Items]
Rate	3.00%
SJWC \| Senior notes \| Maximum
Debt Instrument [Line Items]
Rate	7.37%
SJWC \| Public utility, bonds \| California Pollution Control Financing Authority Revenue Bond
Debt Instrument [Line Items]
Total debt	$ 70,000	70,000
SJWC \| Public utility, bonds \| California Pollution Control Financing Authority Revenue Bond \| Minimum
Debt Instrument [Line Items]
Rate	4.75%
SJWC \| Public utility, bonds \| California Pollution Control Financing Authority Revenue Bond \| Maximum
Debt Instrument [Line Items]
Rate	4.75%
CTWS \| Bank term loans
Debt Instrument [Line Items]
Total debt	$ 16,457	18,444
CTWS \| Bank term loans \| Minimum
Debt Instrument [Line Items]
Rate	4.09%
CTWS \| Bank term loans \| Maximum
Debt Instrument [Line Items]
Rate	4.15%
Connecticut Water Company
Debt Instrument [Line Items]
Total debt	$ 313,345	313,345
Connecticut Water Company \| Senior notes
Debt Instrument [Line Items]
Total debt	$ 195,000	195,000
Connecticut Water Company \| Senior notes \| Minimum
Debt Instrument [Line Items]
Rate	3.07%
Connecticut Water Company \| Senior notes \| Maximum
Debt Instrument [Line Items]
Rate	4.71%
Connecticut Water Company \| Public utility, bonds \| Connecticut Innovations Revenue Bonds, variable rate
Debt Instrument [Line Items]
Total debt	$ 22,050	22,050
Connecticut Water Company \| Bank term loans
Debt Instrument [Line Items]
Total debt	$ 96,295	96,295
Connecticut Water Company \| Bank term loans \| Minimum
Debt Instrument [Line Items]
Rate	4.04%
Connecticut Water Company \| Bank term loans \| Maximum
Debt Instrument [Line Items]
Rate	4.75%
SJWTX
Debt Instrument [Line Items]
Total debt	$ 60,000	60,000
SJWTX \| Senior notes
Debt Instrument [Line Items]
Total debt	$ 15,000	15,000
SJWTX \| Senior notes \| Minimum
Debt Instrument [Line Items]
Rate	6.27%
SJWTX \| Senior notes \| Maximum
Debt Instrument [Line Items]
Rate	6.27%
SJWTX \| Bank term loans
Debt Instrument [Line Items]
Total debt	$ 45,000	45,000
SJWTX \| Bank term loans \| Minimum
Debt Instrument [Line Items]
Rate	4.01%
SJWTX \| Bank term loans \| Maximum
Debt Instrument [Line Items]
Rate	5.54%
TWR \| TWR seller financing debt
Debt Instrument [Line Items]
Total debt	$ 29,000	0
TWR \| TWR seller financing debt \| Minimum
Debt Instrument [Line Items]
Rate	5.61%
TWR \| TWR seller financing debt \| Maximum
Debt Instrument [Line Items]
Rate	5.61%
Maine Water Company
Debt Instrument [Line Items]
Total debt	$ 64,639	66,999
Maine Water Company \| Public utility, bonds \| Other First Mortgage Bond
Debt Instrument [Line Items]
Total debt	$ 900	1,800
Maine Water Company \| Public utility, bonds \| Other First Mortgage Bond \| Minimum
Debt Instrument [Line Items]
Rate	8.95%
Maine Water Company \| Public utility, bonds \| Other First Mortgage Bond \| Maximum
Debt Instrument [Line Items]
Rate	8.95%
Maine Water Company \| Bank term loans
Debt Instrument [Line Items]
Total debt	$ 49,500	49,500
Maine Water Company \| Bank term loans \| Minimum
Debt Instrument [Line Items]
Rate	3.89%
Maine Water Company \| Bank term loans \| Maximum
Debt Instrument [Line Items]
Rate	5.51%
Maine Water Company \| Revolving Fund Loan \| State revolving fund loans
Debt Instrument [Line Items]
Total debt	$ 14,239	$ 15,699
Maine Water Company \| Revolving Fund Loan \| State revolving fund loans \| Minimum
Debt Instrument [Line Items]
Rate	0.00%
Maine Water Company \| Revolving Fund Loan \| State revolving fund loans \| Maximum
Debt Instrument [Line Items]
Rate	2.23%

Contractual interest rate for funds borrowed, under the debt agreement.

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