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Lines of Credit and Long-Term Liabilities (Details) - USD ($) $ in Thousands		9 Months Ended
	Jul. 11, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 18, 2025	Sep. 12, 2025	Sep. 11, 2025	Jul. 10, 2025	Jun. 11, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Weighted-average interest rate on short-term		5.10%							6.08%
Repayments of lines of credit		$ 357,042	$ 235,149
Line of Credit \| CTWS Credit Agreement Maturing August 2025 \| CTWS
Debt Instrument [Line Items]
Repayments of lines of credit	$ 25,000
Unsecured Debt \| 6.70% Promissory Note Due July 20, 2055 \| MWC
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 25,000
Interest rate							6.70%
Unsecured Debt \| 6.68% Promissory Note Due September 18, 2055 \| TWC, Inc.
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 40,000
Interest rate				6.68%
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Unused portion of line of credit		$ 243,632
Revolving Credit Facility \| Line of Credit \| SJWC Credit Agreement Maturing June 2026
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity								$ 10,000
Revolving Credit Facility \| Line of Credit \| Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					$ 350,000	$ 300,000