Utility Plant and Intangible Assets 2 (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangible assets
Property, Plant and Equipment, Gross		$ 1,620,325	$ 1,527,537
Total amortized intangible assets		37,107	35,664
Less - accumulated amortization		(28,001)	(26,196)
Intangible assets, net of amortization		9,106	9,468
Unamortized intangible assets	[1]	409	409
Amortization of intangible assets		1,900	1,800	$ 1,900
Estimated future consolidated amortization expenses related to intangible assets
2014		1,922
2015		1,922
2016		1,737
2017		1,609
2018		1,485
Total		$ 8,675
Conservation
Intangible assets
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		3 years
Total amortized intangible assets		$ 9,496	9,496
Water and water service rights
Intangible assets
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		30 years
Total amortized intangible assets	[2]	$ 8,124	8,124
Water planning studies
Intangible assets
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		14 years
Total amortized intangible assets		$ 19,487	18,044
GSWC
Intangible assets
Property, Plant and Equipment, Gross		1,608,428	1,516,505
Total amortized intangible assets		37,678	36,235
Less - accumulated amortization		(28,108)	(26,291)
Intangible assets, net of amortization		9,570	9,944
Unamortized intangible assets	[1]	427	427
GSWC | Conservation
Intangible assets
Total amortized intangible assets		9,496	9,496
GSWC | Water and water service rights
Intangible assets
Total amortized intangible assets	[2]	8,695	8,695
GSWC | Water planning studies
Intangible assets
Total amortized intangible assets		19,487	18,044
Intangible Assets [Member] | American States Utility Services [Member]
Intangible assets
Property, Plant and Equipment, Gross		$ 571	$ 571

[1] The intangible assets not subject to amortization primarily consist of organization and consent fees.

[2] Includes intangible assets of $571,000 for contracted services included in "Other Property and Investments" on the consolidated balance sheets as of December 31, 2016 and 2015.