Business Segments: (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Details of reportable segment
Total utility plant	$ 1,594,546	$ 1,479,110	$ 1,594,546	$ 1,479,110	$ 1,512,043
Other assets	280,254	247,308	280,254	247,308
Total Assets	1,874,800	1,726,418	1,874,800	1,726,418	1,791,603
GOLDEN STATE WATER COMPANY
Details of reportable segment
Total utility plant	1,471,740		1,471,740		1,400,489
Total Assets	1,618,114		1,618,114		$ 1,560,782
Golden State Water Company and Bear Valley Electric Service Inc.
Details of reportable segment
Depreciation on transportation equipment	$ 94	$ 84	$ 283	$ 249