Employee Benefit Plans - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) item participant	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost for employees under age of 65 (as a percent)	5.90%
Ultimate health care cost for employees under age of 65 (as a percent)	4.00%
Initial Health care cost for employees of age 65 and over (as a percent)	6.30%
Ultimate health care cost for employees of age 65 and over (as a percent)	4.00%
Employer contribution to the plan	$ 2,900	$ 2,700	$ 2,700
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 2,200	$ 2,000	$ 1,900
Union plan
Defined Benefit Plan Disclosure [Line Items]
Expected long-term return on plan assets	5.50%	5.50%	5.75%
Non-union plan
Defined Benefit Plan Disclosure [Line Items]
Expected long-term return on plan assets	3.90%	3.90%	4.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Minimum age for eligibility under the Pension Plan | item	21
Minimum period of service for eligibility under the Pension Plan	5 years
Normal retirement benefit (as a percent)	2.00%
Defined benefit plan number of highest consecutive years average earnings used in computing retirement benefit	5 years
Maximum number of years of credited service considered in determining retirement benefit	40 years
Number of participants in the Pension Plan | participant	903
Eligibility for employer matching contributions, period of service	3 years
Discount rate	5.16%	5.41%
Regulatory adjustment - deferred	$ (281)	$ 0	$ (1,277)
Employer contributions	2,946	$ 3,089
Expected future employer's contribution	$ 3,300
Expected long-term return on plan assets	5.75%	5.75%	6.00%
Pension Benefits | GSWC
Defined Benefit Plan Disclosure [Line Items]
Regulatory adjustment - deferred	$ (281)	$ (1,500)	$ 1,300
Pension Benefits | BVES
Defined Benefit Plan Disclosure [Line Items]
Regulatory adjustment - deferred	$ (270)	$ (490)	(246)
Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage of participant's eligible pay contributed to the plan by the employer	3.00%
Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of participant's eligible pay contributed to the plan by the employer	5.25%
Post-Retirement Medical Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.04%	5.34%
Regulatory adjustment - deferred	$ 0	$ 0	$ 0
Employer contributions	$ 265	$ 263
Post-Retirement Medical Benefits | Minimum | Fixed income fund
Defined Benefit Plan Disclosure [Line Items]
Maturity period of investments	1 year
Post-Retirement Medical Benefits | Maximum | Fixed income fund
Defined Benefit Plan Disclosure [Line Items]
Maturity period of investments	20 years
SERP
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.15%	5.42%
Balance in Rabbi Trust	$ 34,100