Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	$ 265,630	$ 283,620
Total Regulatory Liabilities	212,664	213,679
Future tax benefits due to customers
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	131,218	131,155
Pension and retiree group health
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	58,678	58,678
HCBA
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	2,771	14,318
PCBA
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	5,799	0
CEBA
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	1,424	6,036
Net WRAM and MCBA long-term payable
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	2,065	172
Other components of net periodic benefit cost
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	7,975	2,475
RSF regulatory liability
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	1,269	0
Other regulatory liabilities
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Liabilities	1,465	845
Retiree group health
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	0	171
Future tax benefits due to customers
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	143,546	143,546
Other accrued benefits
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	25,762	24,946
Net WRAM and MCBA long-term accounts receivable
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	34,810	41,558
Asset retirement obligations, net
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	26,930	24,548
Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	3,407	3,682
Tank coating
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	18,910	16,395
Recoverable property losses
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	2,743	3,144
PCBA
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	$ 3,661	19,091
General district balancing account receivable
Regulatory Assets and Liabilities [Line Items]
Recovery Period	1 year
Total Regulatory Assets	$ 389	377
Customer assistance program (CAP) and Rate support fund (RSF) accounts receivable
Regulatory Assets and Liabilities [Line Items]
Recovery Period	1 year
Total Regulatory Assets	$ 2,450	2,965
Other regulatory assets
Regulatory Assets and Liabilities [Line Items]
Total Regulatory Assets	$ 3,022	$ 3,197
Minimum | Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities [Line Items]
Recovery Period	1 year
Maximum | Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities [Line Items]
Recovery Period	2 years