Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Details of reportable segment
Revenues	$ 161,423	$ 108,570
Operating Income (Loss)	51,165	24,365
Income tax expense	10,752	4,461
Interest Income (Expense), Nonoperating, Net	(7,617)	(5,323)
Total net property, plant and equipment	1,780,461	1,649,859	$ 1,753,766
Depreciation and amortization	11,203	10,114
Property, Plant and Equipment, Additions	49,337	35,170
AWR | Intersegment Eliminations
Details of reportable segment
Revenues	0	0
Operating Income (Loss)	(1)	(2)
Income tax expense	(544)	(124)
Interest Income (Expense), Nonoperating, Net	(1,323)	(200)
Total net property, plant and equipment	0	0
Depreciation and amortization	0	0
Property, Plant and Equipment, Additions	0	0
GOLDEN STATE WATER COMPANY
Details of reportable segment
Revenues	112,712	73,906
Operating Income (Loss)	40,239	16,999
Income tax expense	8,910	2,689
Total net property, plant and equipment	1,638,031		1,616,718
Depreciation and amortization	9,606	8,545
GOLDEN STATE WATER COMPANY | Water:
Details of reportable segment
Revenues	112,712	73,906
GOLDEN STATE WATER COMPANY | Reportable Legal Entities | Water:
Details of reportable segment
Revenues	112,712	73,906
Operating Income (Loss)	40,239	16,999
Income tax expense	8,910	2,689
Interest Income (Expense), Nonoperating, Net	(5,494)	(5,145)
Total net property, plant and equipment	1,638,031	1,523,665
Depreciation and amortization	9,606	8,545
Property, Plant and Equipment, Additions	42,005	31,465
BVES | Electric:
Details of reportable segment
Revenues	12,904	11,892
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Revenues	12,904	11,892
Operating Income (Loss)	3,631	3,598
Income tax expense	701	952
Interest Income (Expense), Nonoperating, Net	(573)	(113)
Total net property, plant and equipment	125,093	107,114
Depreciation and amortization	748	654
Property, Plant and Equipment, Additions	6,652	3,468
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Revenues	35,807	22,772
Operating Income (Loss)	7,296	3,770
Income tax expense	1,685	944
Interest Income (Expense), Nonoperating, Net	(227)	135
Total net property, plant and equipment	17,337	19,080
Depreciation and amortization	849	915
Property, Plant and Equipment, Additions	680	237
Golden State Water Company and Bear Valley Electric Service Inc.
Details of reportable segment
Public Utilities Property Plant and Equipment Depreciation on Transportation Equipment	$ 368	$ 94	$ 212