Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Details of reportable segment
Operating revenues	$ 161,782	$ 151,696	$ 452,361	$ 470,519
Operating income (loss)	55,068	51,751	145,790	161,861
Interest expense (income), net	11,486	9,566	33,315	26,108
Net property, plant and equipment	2,040,589	1,850,471	2,040,589	1,850,471	$ 1,892,280
Depreciation and amortization	10,849	10,184	32,341	31,645
Income tax expense (benefit)	10,056	9,547	27,811	33,503
Capital additions	64,179	47,482	173,477	136,131
AWR | Intersegment Eliminations
Details of reportable segment
Operating revenues	0	0	0	0
Operating income (loss)	(2)	255	(5)	218
Interest expense (income), net	1,365	1,637	4,677	4,389
Net property, plant and equipment	0	0	0	0
Depreciation and amortization	0	0	0	0
Income tax expense (benefit)	(732)	(559)	(1,691)	(1,586)
Capital additions	0	0	0	0
GOLDEN STATE WATER COMPANY
Details of reportable segment
Operating revenues	124,043	116,231	324,732	345,851
Operating income (loss)	46,846	43,243	116,578	134,006
Net property, plant and equipment	1,861,431		1,861,431		$ 1,735,534
Depreciation and amortization	9,070	8,610	27,147	26,890
Income tax expense (benefit)	9,228	8,830	23,539	29,674
GOLDEN STATE WATER COMPANY | Water:
Details of reportable segment
Operating revenues	124,043	116,231	324,732	345,851
Public utilities property plant and equipment depreciation on transportation equipment				200
GOLDEN STATE WATER COMPANY | Reportable Legal Entities | Water:
Details of reportable segment
Operating revenues	124,043	116,231	324,732	345,851
Operating income (loss)	46,846	43,243	116,578	134,006
Interest expense (income), net	8,358	6,775	24,381	18,784
Net property, plant and equipment	1,861,431	1,696,923	1,861,431	1,696,923
Depreciation and amortization	9,070	8,610	27,147	26,890
Income tax expense (benefit)	9,228	8,830	23,539	29,674
Capital additions	51,466	37,349	147,093	113,921
BVES | Electric:
Details of reportable segment
Operating revenues	9,040	8,956	29,948	30,688
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Operating revenues	9,040	8,956	29,948	30,688
Operating income (loss)	2,042	2,049	6,416	7,783
Interest expense (income), net	1,346	760	3,162	1,987
Net property, plant and equipment	161,788	137,299	161,788	137,299
Depreciation and amortization	944	776	2,721	2,283
Income tax expense (benefit)	135	(154)	656	794
Capital additions	11,862	9,947	23,023	20,985
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Operating revenues	28,699	26,509	97,681	93,980
Operating income (loss)	6,182	6,204	22,801	19,854
Interest expense (income), net	417	394	1,095	948
Net property, plant and equipment	17,370	16,249	17,370	16,249
Depreciation and amortization	835	798	2,473	2,472
Income tax expense (benefit)	1,425	1,430	5,307	4,621
Capital additions	851	186	3,361	1,225
Golden State Water Company and Bear Valley Electric Service Inc.
Details of reportable segment
Public utilities property plant and equipment depreciation on transportation equipment	$ 200	$ 200	$ 500	$ 700