Utility Plant and Intangible Assets (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		$ 2,178,349	$ 2,052,353
Less — accumulated depreciation		(606,231)	(594,264)
Construction work in progress		181,648	167,915
Net utility plant		1,753,766	1,626,004	$ 1,512,043
American States Utility Services | Intangible Assets [Member]
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		571	571
Water Service Utility Operations
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		2,044,534	1,935,881
Water Service Utility Operations | Land
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		18,427	18,207
Water Service Utility Operations | Intangible Assets [Member]
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		30,511	29,028
Water Service Utility Operations | Source of water supply
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		109,918	98,244
Water Service Utility Operations | Pumping
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		227,668	209,936
Water Service Utility Operations | Water treatment
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		90,411	83,922
Water Service Utility Operations | Transmission and distribution
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		1,431,437	1,356,649
Water Service Utility Operations | General
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		136,162	139,895
Electric:
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		133,815	116,472
Electric: | Intangible Assets [Member]
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		1,200	1,200
Electric: | Transmission and distribution
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		105,499	90,491
Electric: | Generation
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		12,583	12,583
Electric: | General
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost	[1]	15,733	13,398
GSWC
Utility plant utilized in continuing operations by major asset class
Less — accumulated depreciation		(530,925)	(522,672)
Construction work in progress		141,175	123,600
Net utility plant		1,616,718	1,499,745
GSWC | Water Service Utility Operations
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		2,006,468	1,898,817
Net utility plant		1,616,718	1,499,745	1,400,489
GSWC | Water Service Utility Operations | Land
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		18,427	18,207
GSWC | Water Service Utility Operations | Intangible Assets [Member]
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		30,511	29,028
GSWC | Water Service Utility Operations | Source of water supply
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		109,918	98,244
GSWC | Water Service Utility Operations | Pumping
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		227,668	209,936
GSWC | Water Service Utility Operations | Water treatment
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		90,411	83,922
GSWC | Water Service Utility Operations | Transmission and distribution
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		1,431,437	1,356,649
GSWC | Water Service Utility Operations | General
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		98,096	102,831
GSWC | Electric:
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		0	0
Net utility plant			106,508	$ 89,308
GSWC | Electric: | Transmission and distribution
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		0	0
GSWC | Electric: | Generation
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost		0	0
GSWC | Electric: | General
Utility plant utilized in continuing operations by major asset class
Total utility plant, at cost	[1]	$ 0	$ 0

[1]      Includes intangible assets of $1.2 million for the years ended December 31, 2022 and 2021 for studies performed in association with the electric segment.