Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Details of reportable segment
Operating revenues	$ 155,328	$ 157,400	$ 290,579	$ 318,823
Operating income (loss)	51,748	58,945	90,722	110,110
Interest expense (income), net	11,044	8,925	21,829	16,542
Net property, plant and equipment	1,981,636	1,814,061	1,981,636	1,814,061	$ 1,892,280
Depreciation and amortization	10,770	10,258	21,492	21,461
Income tax expense	10,359	13,204	17,755	23,956
Segment, Expenditure, Addition to Long-Lived Assets	61,748	39,312	109,298	88,649
AWR | Intersegment Eliminations
Details of reportable segment
Operating revenues	0	0	0	0
Operating income (loss)	(2)	(36)	(3)	(37)
Interest expense (income), net	1,590	1,429	3,312	2,752
Net property, plant and equipment	0	0	0	0
Depreciation and amortization	0	0	0	0
Income tax expense	(411)	(483)	(959)	(1,027)
Segment, Expenditure, Addition to Long-Lived Assets	0	0	0	0
GOLDEN STATE WATER COMPANY
Details of reportable segment
Operating revenues	110,424	116,908	200,689	229,620
Operating income (loss)	40,565	50,524	69,732	90,763
Net property, plant and equipment	1,813,292		1,813,292		$ 1,735,534
Depreciation and amortization	9,043	8,674	18,077	18,280
Income tax expense	8,487	11,934	14,311	20,844
GOLDEN STATE WATER COMPANY | Water:
Details of reportable segment
Operating revenues	110,424	116,908	200,689	229,620
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	110,424	116,908	200,689	229,620
Operating income (loss)	40,565	50,524	69,732	90,763
Interest expense (income), net	8,142	6,515	16,023	12,009
Net property, plant and equipment	1,813,292	1,666,700	1,813,292	1,666,700
Depreciation and amortization	9,043	8,674	18,077	18,280
Income tax expense	8,487	11,934	14,311	20,844
Segment, Expenditure, Addition to Long-Lived Assets	54,349	34,567	95,627	76,572
BVES | Electric:
Details of reportable segment
Operating revenues	8,703	8,828	20,908	21,732
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Operating revenues	8,703	8,828	20,908	21,732
Operating income (loss)	1,233	2,103	4,374	5,734
Interest expense (income), net	951	654	1,816	1,227
Net property, plant and equipment	150,999	130,502	150,999	130,502
Depreciation and amortization	893	759	1,777	1,507
Income tax expense	(39)	247	521	948
Segment, Expenditure, Addition to Long-Lived Assets	5,945	4,386	11,161	11,038
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Operating revenues	36,201	31,664	68,982	67,471
Operating income (loss)	9,952	6,354	16,619	13,650
Interest expense (income), net	361	327	678	554
Net property, plant and equipment	17,345	16,859	17,345	16,859
Depreciation and amortization	834	825	1,638	1,674
Income tax expense	2,322	1,506	3,882	3,191
Segment, Expenditure, Addition to Long-Lived Assets	1,454	359	2,510	1,039
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	$ 300	$ 500