Long-Term Water Assets - Additional Information (Details)	6 Months Ended
	Jun. 30, 2019 USD ($) acre ft	Jun. 30, 2018 USD ($)	Dec. 31, 2018 acre ft	Dec. 31, 2013 acre ft	Dec. 31, 2009 acre ft
Long Lived Assets Held-for-sale [Line Items]
Contract renewal optional term	35 years
Cost of purchased water (per acre-foot) | $	$ 3,194,000	$ 3,679,000
AVEK water bank
Long Lived Assets Held-for-sale [Line Items]
AVEK water bank (in acre-feet)	0		13,033,000
SWP water contracts
Long Lived Assets Held-for-sale [Line Items]
AVEK water for future delivery (in acre-feet)					3,444
DMB
Long Lived Assets Held-for-sale [Line Items]
Contract renewal optional term	35 years
Cost of purchased water (per acre-foot) | $	$ 769
DMB | Maximum
Long Lived Assets Held-for-sale [Line Items]
Annual fee increase, percent	3.00%
DMB | Transferable water
Long Lived Assets Held-for-sale [Line Items]
Long-term water assets (in acre-feet)	6,693			6,693
PEF | Transferable water | Ranchcorp
Long Lived Assets Held-for-sale [Line Items]
Cost of purchased water (per acre-foot) | $	$ 1,120
Annual fee increase, percent	3.00%
Water assets, volume available for purchase from 2017-2030 (up to) (in acre-feet)	3,500
Annual option payment, percent	30.00%