Business Segments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Details of reportable segment
Operating revenues	$ 595,699	$ 491,528	$ 498,853
Operating income (loss)	196,740	126,636	140,977
Interest expense (income), net	35,346	24,701	21,341
Net utility plant	1,892,280	1,753,766	1,626,004
Depreciation and amortization expense	42,403	41,315	39,596
Income tax benefit	41,599	23,664	30,423
Capital additions	$ 188,540	166,240	144,515
GSWC
Details of reportable segment
Number of reportable segments | segment	1
Operating revenues	$ 433,473	340,602	347,112
Operating income (loss)	159,177	92,455	107,573
Net utility plant	1,735,534	1,616,718
Depreciation and amortization expense	35,886	34,805	33,384
Income tax benefit	35,689	16,346	22,095
Depreciation on transportation equipment	212
GSWC | Water
Details of reportable segment
Operating revenues	433,473	340,602	347,112
Operating income (loss)	159,177	92,455	107,573
Interest expense (income), net	25,726	21,659	21,046
Net utility plant	1,735,534	1,616,718	1,499,745
Depreciation and amortization expense	35,886	34,805	33,384
Income tax benefit	35,689	16,346	22,095
Capital additions	160,939	146,730	123,526
BVES | Electric
Details of reportable segment
Operating revenues	41,832	39,986	38,345
Operating income (loss)	11,196	11,740	10,738
Interest expense (income), net	2,238	831	141
Net utility plant	140,279	119,560	106,508
Depreciation and amortization expense	3,256	2,792	2,572
Income tax benefit	1,515	2,439	2,975
Capital additions	25,372	18,069	19,859
American States Utility Services | Contracted services:
Details of reportable segment
Operating revenues	120,394	110,940	113,396
Operating income (loss)	26,151	22,449	22,675
Interest expense (income), net	1,321	(132)	(637)
Net utility plant	16,467	17,488	19,751
Depreciation and amortization expense	3,261	3,718	3,640
Income tax benefit	6,109	5,476	5,434
Capital additions	2,229	1,441	1,130
Golden State Water Company and Bear Valley Electric Service, Inc.
Details of reportable segment
Depreciation on transportation equipment	$ 851	382	379
Parent Company
Details of reportable segment
Number of reportable segments | segment	3
Operating revenues	$ 0	0	0
Interest expense (income), net	6,061	2,343	791
Net utility plant	0	0	0
Depreciation and amortization expense	0	0	0
Income tax benefit	(1,714)	(597)	(81)
Capital additions	0	0	0
Parent Company | Intersegment Eliminations
Details of reportable segment
Operating income (loss)	$ 216	$ (8)	$ (9)