Long-Term Water Assets - Volume of Water Assets (Details)	Dec. 31, 2018 acre ft	Dec. 31, 2017 acre ft	Dec. 31, 2009 acre ft	Dec. 31, 2008 acre ft
Water held for future use
Purchased water contracts	10,137	10,137
Total purchased water contracts	83,980	80,617
Total water held for future use and purchased water contracts	133,306	131,316
Transferable water
Water held for future use
AVEK water bank		6,169
AVEK
Water held for future use
AVEK water bank	13,033	13,033	6,393	8,393
Company water bank	35,793	31,497
Transferable water	500	6,169
Total water held for future use	49,326	50,699
AVEK | Transferable water
Water held for future use
AVEK water bank		1,452
Transferable water		2,137
Transferable water factor		1.5
Wheeler Ridge Maricopa Water Storage District
Water held for future use
Purchased water contracts	15,547	15,547
Tejon-Castac Water District
Water held for future use
Total water held for future use	52,547	49,184
Purchased water contracts	5,749	5,749