CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Operating revenue	$ 270,749	$ 131,100
Operations:
Water production costs	64,185	55,008
Administrative and general	35,596	35,986
Other operations	26,925	16,604
Maintenance	8,010	7,978
Depreciation and amortization	32,844	29,915
Income tax expense (benefit)	15,538	(5,644)
Property and other taxes	9,757	8,777
Total operating expenses	192,855	148,624
Net operating income (loss)	77,894	(17,524)
Other income and expenses:
Non-regulated revenue	5,098	4,623
Non-regulated expenses	(1,954)	(2,275)
Other components of net periodic benefit credit	3,273	5,221
Allowance for equity funds used during construction	1,742	1,404
Income tax expense on other income and expenses	(1,321)	(1,794)
Net other income	6,838	7,179
Interest expense:
Interest expense	15,800	12,818
Allowance for borrowed funds used during construction	(758)	(829)
Net interest expense	15,042	11,989
Net income (loss)	69,690	(22,334)
Net loss attributable to noncontrolling interests	(227)	(123)
Net income (loss) attributable to California Water Service Group	$ 69,917	$ (22,211)
Earnings (loss) per share:
Basic (in dollars per share)	$ 1.21	$ (0.40)
Diluted (in dollars per share)	$ 1.21	$ (0.40)
Weighted average shares outstanding:
Basic (in shares)	57,733	55,666
Diluted (in shares)	57,774	55,666