CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Operating revenue	$ 131,100	$ 172,993
Operations:
Water production costs	55,008	61,538
Administrative and general	35,986	33,411
Other operations	16,604	25,852
Maintenance	7,978	7,341
Depreciation and amortization	29,915	28,770
Income tax benefit	(5,644)	(1,417)
Property and other taxes	8,777	8,360
Total operating expenses	148,624	163,855
Net operating income	(17,524)	9,138
Other income and expenses:
Non-regulated revenue	4,623	5,197
Non-regulated expenses	(2,275)	(6,986)
Other components of net periodic benefit credit	5,221	4,014
Allowance for equity funds used during construction	1,404	975
Income tax expense on other income and expenses	(1,794)	(512)
Net other income	7,179	2,688
Interest expense:
Interest expense	12,818	11,495
Allowance for borrowed funds used during construction	(829)	(563)
Net interest expense	11,989	10,932
Net income	(22,334)	894
Net (loss) income attributable to noncontrolling interests	(123)	(192)
Net income attributable to California Water Service Group	$ (22,211)	$ 1,086
Earnings per share of common stock:
Basic (in dollars per share)	$ (0.40)	$ 0.02
Diluted (in dollars per share)	$ (0.40)	$ 0.02
Weighted average shares outstanding:
Basic (in shares)	55,666	53,731
Diluted (in shares)	55,666	53,775