Business Segments - Schedule of PPE and Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Details of reportable segment
Total net property, plant and equipment (4)	$ 2,367,219	$ 2,296,319
Other assets	407,741	418,773
Total Assets	2,774,960	2,715,092
Reportable Legal Entities
Details of reportable segment
Total net property, plant and equipment (4)	2,367,219	2,296,319
Other assets	408,240	420,543
Total Assets	2,775,459	2,716,862
Intersegment Eliminations
Details of reportable segment
Total net property, plant and equipment (4)	0	0
Other assets	(1,205,149)	(1,178,530)
Total Assets	(1,205,149)	(1,178,530)
AWR | Intersegment Eliminations
Details of reportable segment
Total net property, plant and equipment (4)	0	0
Other assets	1,204,650	1,176,760
Total Assets	1,204,650	1,176,760
GOLDEN STATE WATER COMPANY
Details of reportable segment
Total net property, plant and equipment (4)	2,148,879	2,083,684
Total Assets	2,382,965	2,315,862
GOLDEN STATE WATER COMPANY | Reportable Legal Entities | Water:
Details of reportable segment
Total net property, plant and equipment (4)	2,148,879	2,083,684
Other assets	234,086	232,178
Total Assets	2,382,965	2,315,862
BVES | Reportable Legal Entities | Electric:
Details of reportable segment
Total net property, plant and equipment (4)	197,593	192,416
Other assets	56,936	61,928
Total Assets	254,529	254,344
ASUS | Reportable Legal Entities | Contracted services:
Details of reportable segment
Total net property, plant and equipment (4)	20,747	20,219
Other assets	117,218	126,437
Total Assets	$ 137,965	$ 146,656