v3.25.4
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