Long-Term Water Assets - Tangible Water Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Long Lived Assets Held For Sale [Line Items]
Total water held for future use at cost	$ 24,633	$ 18,571
Banked water and water for future delivery
Long Lived Assets Held For Sale [Line Items]
Total water held for future use at cost	24,597	5,220
Transferable water
Long Lived Assets Held For Sale [Line Items]
Total water held for future use at cost	$ 36	$ 13,351