Long Term Water Assets - Volume of Water Assets (Details)	Dec. 31, 2017 acre ft	Dec. 31, 2016 acre ft	Dec. 31, 2009 acre ft	Dec. 31, 2008 acre ft
Water held for future use
Purchased water contracts	10,137	10,137
Long-term Water Assets, Intangible Water Contracts (Volume)	80,617	64,823
Total water held for future use and purchased water contracts	131,316	106,567
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	31,497	17,287
AVEK water for future delivery	0	2,362
Transferable water	6,169	9,062
Total water held for future use	50,699	41,744
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	49,184	33,390
Purchased water contracts	5,749	5,749