CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Income Statement [Abstract]
Operating revenue	$ 264,954	$ 244,299	$ 468,927	$ 515,048
Operations:
Water production costs	85,503	77,644	148,494	141,829
Administrative and general	33,317	32,042	67,491	67,638
Other operations	31,695	25,626	60,531	52,551
Maintenance	9,043	8,790	16,711	16,800
Depreciation and amortization	36,029	32,978	71,985	65,822
Income taxes	6,915	8,689	7,950	24,227
Property and other taxes	10,643	10,364	21,611	20,121
Total operating expenses	213,145	196,133	394,773	388,988
Net operating income	51,809	48,166	74,154	126,060
Other income and expenses:
Non-regulated revenue	4,911	5,513	9,992	10,611
Non-regulated expenses	(2,868)	(4,125)	(6,334)	(6,079)
Other components of net periodic benefit credit	4,589	4,338	9,389	7,611
Allowance for equity funds used during construction	1,898	1,819	3,695	3,561
Income taxes on other income and expenses	(1,752)	(1,306)	(3,455)	(2,627)
Net other income	6,778	6,239	13,287	13,077
Interest expense:
Interest expense	17,464	14,840	33,973	30,640
Allowance for borrowed funds used during construction	(927)	(812)	(1,784)	(1,570)
Net interest expense	16,537	14,028	32,189	29,070
Net income	42,050	40,377	55,252	110,067
Net loss attributable to noncontrolling interest	(118)	(174)	(247)	(401)
Net income attributable to California Water Service Group	$ 42,168	$ 40,551	$ 55,499	$ 110,468
Earnings per share:
Basic (in dollars per share)	$ 0.71	$ 0.70	$ 0.93	$ 1.90
Diluted (in dollars per share)	$ 0.71	$ 0.70	$ 0.93	$ 1.90
Weighted average shares outstanding:
Basic (in shares)	59,574	58,292	59,542	58,013
Diluted (in shares)	59,629	58,325	59,590	58,046