Long-Term Water Assets Long-Term Water Assets - Tangible Water Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Long Lived Assets Held-for-sale [Line Items]
Total tangible water	$ 21,153	$ 18,571
Banked water and water for future delivery
Long Lived Assets Held-for-sale [Line Items]
Total tangible water	5,428	5,220
Transferable water
Long Lived Assets Held-for-sale [Line Items]
Total tangible water	$ 15,725	$ 13,351