CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Operating revenue	$ 172,993	$ 147,737
Operations:
Water production costs	61,538	54,826
Administrative and general	33,411	30,369
Other operations	25,852	17,912
Maintenance	7,341	6,769
Depreciation and amortization	28,770	27,047
Income tax benefit	(1,417)	(101)
Property and other taxes	8,360	7,996
Total operating expenses	163,855	144,818
Net operating income	9,138	2,919
Other income and expenses:
Non-regulated revenue	5,197	5,572
Non-regulated expenses	(6,986)	(4,760)
Other components of net periodic benefit credit	4,014	2,979
Allowance for equity funds used during construction	975	544
Income tax expense on other income and expenses	(512)	(358)
Net other income	2,688	3,977
Interest expense:
Interest expense	11,495	10,222
Allowance for borrowed funds used during construction	(563)	(294)
Net interest expense	10,932	9,928
Net income (loss)	894	(3,032)
Net loss attributable to noncontrolling interests	(192)	0
Net income (loss) attributable to California Water Service Group	$ 1,086	$ (3,032)
Earnings (loss) per share of common stock:
Basic (in dollars per share)	$ 0.02	$ (0.06)
Diluted (in dollars per share)	$ 0.02	$ (0.06)
Weighted average shares outstanding:
Basic (in shares)	53,731	50,440
Diluted (in shares)	53,775	50,440