Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Details of reportable segment
Operating revenues	$ 151,696	$ 134,984	$ 470,519	$ 366,161
Operating income (loss)	51,751	40,340	161,861	99,022
Interest expense (income), net	9,566	6,664	26,108	17,859
Net property, plant and equipment	1,850,471	1,718,152	1,850,471	1,718,152	$ 1,753,766
Depreciation and amortization	10,184	10,117	31,645	30,402
Income tax expense	9,547	8,360	33,503	19,026
Capital additions	47,482	45,504	136,131	122,056
AWR | Intersegment Eliminations
Details of reportable segment
Operating revenues	0	0	0	0
Operating income (loss)	255	(1)	218	(6)
Interest expense (income), net	1,637	711	4,389	1,272
Net property, plant and equipment	0	0	0	0
Depreciation and amortization	0	0	0	0
Income tax expense	(559)	(296)	(1,586)	(641)
Capital additions	0	0	0	0
GOLDEN STATE WATER COMPANY
Details of reportable segment
Operating revenues	116,231	100,799	345,851	265,561
Operating income (loss)	43,243	32,451	134,006	77,161
Net property, plant and equipment	1,696,923		1,696,923		$ 1,616,718
Depreciation and amortization	8,610	8,475	26,890	25,573
Income tax expense	8,830	6,831	29,674	14,623
GOLDEN STATE WATER COMPANY | Water:
Details of reportable segment
Operating revenues	116,231	100,799	345,851	265,561
Public Utilities Property Plant and Equipment Depreciation on Transportation Equipment			212
GOLDEN STATE WATER COMPANY | Reportable Legal Entities | Water:
Details of reportable segment
Operating revenues	116,231	100,799	345,851	265,561
Operating income (loss)	43,243	32,451	134,006	77,161
Interest expense (income), net	6,775	5,625	18,784	16,088
Net property, plant and equipment	1,696,923	1,584,888	1,696,923	1,584,888
Depreciation and amortization	8,610	8,475	26,890	25,573
Income tax expense	8,830	6,831	29,674	14,623
Capital additions	37,349	40,684	113,921	107,668
BVES | Electric:
Details of reportable segment
Operating revenues	8,956	8,919	30,688	29,028
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Operating revenues	8,956	8,919	30,688	29,028
Operating income (loss)	2,049	2,337	7,783	7,973
Interest expense (income), net	760	355	1,987	763
Net property, plant and equipment	137,299	115,379	137,299	115,379
Depreciation and amortization	776	709	2,283	2,049
Income tax expense	(154)	478	794	1,645
Capital additions	9,947	4,711	20,985	13,485
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Operating revenues	26,509	25,266	93,980	71,572
Operating income (loss)	6,204	5,553	19,854	13,894
Interest expense (income), net	394	(27)	948	(264)
Net property, plant and equipment	16,249	17,885	16,249	17,885
Depreciation and amortization	798	933	2,472	2,780
Income tax expense	1,430	1,347	4,621	3,399
Capital additions	186	109	1,225	903
Golden State Water Company and Bear Valley Electric Service Inc.
Details of reportable segment
Public Utilities Property Plant and Equipment Depreciation on Transportation Equipment	$ 160	$ 97	$ 683	$ 286