Long-Term Water Assets Long-Term Water Assets - Intangible Water Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Costs	$ 36,800	$ 36,800
Accumulated Depreciation	(8,579)	(8,241)
Net intangible water assets	28,221	28,559
Total tangible water assets	21,257	18,571
Net investment in water assets	49,478	47,130
Contract-based intangible assets | Dudley Ridge water rights
Finite-Lived Intangible Assets [Line Items]
Costs	12,203	12,203
Accumulated Depreciation	(3,498)	(3,377)
Contract-based intangible assets | Nickel water rights
Finite-Lived Intangible Assets [Line Items]
Costs	18,740	18,740
Accumulated Depreciation	(2,838)	(2,678)
Contract-based intangible assets | Tulare Lake Basin water rights
Finite-Lived Intangible Assets [Line Items]
Costs	5,857	5,857
Accumulated Depreciation	$ (2,243)	$ (2,186)