Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Adjustment to pension benefit plans, net of taxes	$ 493,000	$ (611,000)	$ 216,000
Value of life insurance contracts	4,852,000	4,294,000
Annual maximum contribution limit under Health Care Spending Account plan	3,300
Annual maximum contribution limit under Dependent Care Spending Account plan	5,000
Employer contributions to deferral plan	$ 4,928,000	4,221,000	3,902,000
Health care cost trend rate assumed, next fiscal year	8.00%
Ultimate health care cost trend rate	4.50%
Actuarial gain (loss), discount rate change	$ (4,219,000)	21,129,000
Actuarial gain (loss), data and other changes	873,000	(6,005,000)
Defined benefit plan, accumulated benefit obligation	269,908,000	263,607,000
Regulatory assets	0
Estimated required and discretionary employer cash contributions	7,682,000
Unrecognized pensions and other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory liabilities	32,996,000	27,872,000
Other comprehensive income (loss), defined benefit plan, gain (loss) arising during period	32,996,000	27,872,000
Unrecognized pensions and other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets		3,177,000
Other comprehensive income (loss), defined benefit plan, gain (loss) arising during period		(3,150,000)
Other comprehensive (income) loss, defined benefit plan, prior service cost (credit)		27,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	293,142,000	287,044,000	297,834,000
Net periodic pension cost	608,000	3,205,000	8,588,000
Total investments made to fund SERP	5,675,000	8,007,000
Executive Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	43,644,000	40,328,000
Net periodic pension cost	3,212,000	3,879,000	3,257,000
Adjustment to pension benefit plans, net of taxes	(493,000)	169,000	$ 314,000
Total investments made to fund SERP	$ 7,887,000	$ 7,336,000
Minimum
Defined Benefit Plan Disclosure [Line Items]
Period for performance standards	3 years
Minimum | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost, expected return on plan assets	6.50%	6.25%	6.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Period for performance standards	5 years
Maximum | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost, expected return on plan assets	6.75%	6.75%	6.75%
TWC Employees
Defined Benefit Plan Disclosure [Line Items]
Interest credits assumption rate	4.25%
TWC Employees | Minimum
Defined Benefit Plan Disclosure [Line Items]
Interest credits rate	3.25%
TWC Employees | Maximum
Defined Benefit Plan Disclosure [Line Items]
Interest credits rate	6.00%
CTWS Employees
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase to company sponsored savings plan	3.00%
Executives and Non-employee Directors | Deferred compensation arrangement with individual, by type of compensation, pension and other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Deferrals by executives and non-employee directors	$ 8,767,000	$ 8,216,000
Executives and Non-employee Directors | Deferred compensation arrangement with individual, by type of compensation, pension and other postretirement benefits | CWC
Defined Benefit Plan Disclosure [Line Items]
Deferrals by executives and non-employee directors	$ 6,552,000	$ 6,276,000