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Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Payment for pension benefits |  | $ 10,000 | $ 42,000 | $ 42,000
Settlement loss |  |  | $ 11,800 |
Percentage of service related net periodic benefit costs capitalized to utility property |  | 40.00% |  |
Percentage of service related net periodic benefit costs recorded to operating expenses |  | 60.00% |  |
Partial Settlement of Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Regulatory asset amortization period |  |  | 12 years |
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Executive Officer [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Deferred compensation, earlier of retirement, termination, disability or death, percent |  | 75.00% |  |
Deferred compensation incentive payments, percent |  | 100.00% |  |
Equity Securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target investment allocation |  | 55.00% | 55.00% |
Debt Securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target investment allocation |  | 40.00% | 40.00% |
Real Estate [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target investment allocation |  | 5.00% | 5.00% |
Pension Plans, Defined Benefit [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected contributions to pension plan |  | $ 10,000 |  |
Settlement loss | [1] |  | $ 11,828 |
Fair value of plan assets |  | 589,983 | 540,703 | 750,963
Other Postretirement Benefits [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected contributions to pension plan |  | 7,100 |  |
Fair value of plan assets |  | $ 58,126 | $ 49,472 | $ 59,544
Other Postretirement Benefits [Member] | Equity Securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target investment allocation |  | 60.00% | 60.00% |
Other Postretirement Benefits [Member] | Debt Securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target investment allocation |  | 40.00% | 40.00% |
Other Postretirement Benefits [Member] | Balanced Mutual Funds [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | $ 58,100 | $ 49,500 |
[1] | The settlement loss was deferred as a regulatory asset and is being amortized over 12 years in accordance with regulatory accounting orders.

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