Long Term Water Assets Long Term Water Assets - Intangible Water Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Costs	$ 36,800	$ 36,800
Accumulated Depreciation	(8,241)	(6,890)
Net cost of purchased water contracts	28,559	29,910
Total cost water held for future use	18,571	13,854
Net investment in water assets	47,130	43,764
Contract-based intangible assets | Dudley Ridge water rights
Finite-Lived Intangible Assets [Line Items]
Costs	12,203	12,203
Accumulated Depreciation	(3,377)	(2,895)
Contract-based intangible assets | Nickel water rights
Finite-Lived Intangible Assets [Line Items]
Costs	18,740	18,740
Accumulated Depreciation	(2,678)	(2,218)
Contract-based intangible assets | Tulare Lake Basin water rights
Finite-Lived Intangible Assets [Line Items]
Costs	5,857	5,857
Accumulated Depreciation	$ (2,186)	$ (1,777)