Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Regulatory Assets and Liabilities
Total Regulatory Assets	$ 276,592	$ 283,620
Total Regulatory Liabilities	206,971	213,679
Future tax benefits due to customers
Regulatory Assets and Liabilities
Total Regulatory Liabilities	131,218	131,155
Pension and retiree group health
Regulatory Assets and Liabilities
Total Regulatory Liabilities	58,678	58,678
HCBA
Regulatory Assets and Liabilities
Total Regulatory Liabilities	3,041	14,318
PCBA
Regulatory Assets and Liabilities
Total Regulatory Liabilities	3,862	0
CEBA
Regulatory Assets and Liabilities
Total Regulatory Liabilities	912	6,036
Net WRAM and MCBA long-term payable
Regulatory Assets and Liabilities
Total Regulatory Liabilities	1,826	172
Other components of net periodic benefit cost
Regulatory Assets and Liabilities
Total Regulatory Liabilities	6,040	2,475
Other regulatory liabilities
Regulatory Assets and Liabilities
Total Regulatory Liabilities	1,394	845
Retiree group health
Regulatory Assets and Liabilities
Total Regulatory Assets	0	171
Future tax benefits due to customers
Regulatory Assets and Liabilities
Total Regulatory Assets	143,546	143,546
Other accrued benefits
Regulatory Assets and Liabilities
Total Regulatory Assets	26,085	24,946
Net WRAM and MCBA long-term accounts receivable
Regulatory Assets and Liabilities
Total Regulatory Assets	45,034	41,558
Asset retirement obligations, net
Regulatory Assets and Liabilities
Total Regulatory Assets	26,129	24,548
Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities
Total Regulatory Assets	3,416	3,682
Tank coating
Regulatory Assets and Liabilities
Total Regulatory Assets	18,920	16,395
Recoverable property losses
Regulatory Assets and Liabilities
Total Regulatory Assets	2,890	3,144
PCBA
Regulatory Assets and Liabilities
Total Regulatory Assets	$ 3,933	19,091
General district balancing account receivable
Regulatory Assets and Liabilities
Recovery Period	1 year
Total Regulatory Assets	$ 387	377
Customer assistance program (CAP) and Rate support fund (RSF) accounts receivable
Regulatory Assets and Liabilities
Recovery Period	1 year
Total Regulatory Assets	$ 3,281	2,965
Other regulatory assets
Regulatory Assets and Liabilities
Total Regulatory Assets	$ 2,971	$ 3,197
Minimum | Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities
Recovery Period	1 year
Maximum | Interim rates memorandum account (IRMA) long-term accounts receivable
Regulatory Assets and Liabilities
Recovery Period	2 years