CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Net income	$ 4,037	$ 13,202
Other comprehensive income:
Amortization of defined benefit pension plans, net of tax of $150 and $60, respectively	385	154
Other comprehensive income, net of tax	385	154
Comprehensive income	4,422	13,356
Comprehensive loss attributable to noncontrolling interest	0	(129)
Comprehensive income attributable to California Water Service Group	$ 4,422	$ 13,485