Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Details of reportable segment
Operating revenues	$ 135,251	$ 161,423
Operating income (loss)	38,974	51,165
Interest expense (income), net	10,785	7,617
Net property, plant and equipment	1,933,694	1,780,461	$ 1,892,280
Depreciation and amortization	10,722	11,203
Income tax expense	7,396	10,752
Segment, Expenditure, Addition to Long-Lived Assets	47,550	49,337
AWR | Intersegment Eliminations
Details of reportable segment
Operating revenues	0	0
Operating income (loss)	(1)	(1)
Interest expense (income), net	1,722	1,323
Net property, plant and equipment	0	0
Depreciation and amortization	0	0
Income tax expense	(548)	(544)
Segment, Expenditure, Addition to Long-Lived Assets	0	0
GOLDEN STATE WATER COMPANY
Details of reportable segment
Operating revenues	90,265	112,712
Operating income (loss)	29,167	40,239
Net property, plant and equipment	1,771,683		$ 1,735,534
Depreciation and amortization	9,034	9,606
Income tax expense	5,824	8,910
GOLDEN STATE WATER COMPANY | Water:
Details of reportable segment
Operating revenues	90,265	112,712
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	90,265	112,712
Operating income (loss)	29,167	40,239
Interest expense (income), net	7,881	5,494
Net property, plant and equipment	1,771,683	1,638,031
Depreciation and amortization	9,034	9,606
Income tax expense	5,824	8,910
Segment, Expenditure, Addition to Long-Lived Assets	41,278	42,005
BVES | Electric:
Details of reportable segment
Operating revenues	12,205	12,904
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Operating revenues	12,205	12,904
Operating income (loss)	3,141	3,631
Interest expense (income), net	865	573
Net property, plant and equipment	145,289	125,093
Depreciation and amortization	884	748
Income tax expense	560	701
Segment, Expenditure, Addition to Long-Lived Assets	5,216	6,652
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Operating revenues	32,781	35,807
Operating income (loss)	6,667	7,296
Interest expense (income), net	317	227
Net property, plant and equipment	16,722	17,337
Depreciation and amortization	804	849
Income tax expense	1,560	1,685
Segment, Expenditure, Addition to Long-Lived Assets	1,056	680
Golden State Water Company and Bear Valley Electric Service Inc.
Details of reportable segment
Public Utilities Property Plant and Equipment Depreciation on Transportation Equipment	$ 163	$ 368