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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 |

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