Revenue Deferred Revenue and Related Costs Oxide Plant Lease and Oxide Plant Lease Costs (Details) $ / shares in Units, $ in Thousands, shares in Millions				1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 03, 2019 $ / item	Dec. 02, 2019 $ / item	Aug. 02, 2017 USD ($) $ / shares shares	Aug. 31, 2017	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Right	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Oxide plant lease					$ 1,224	$ 1,976	$ 2,420	$ 3,908
Lease related costs					420	$ 613	984	1,210
Increase (Decrease) in Deferred Revenue							(245)	(146)
Lease payment							125
Variable fee (per tonne) | $ / item	11.00	22.00
Oxide Plant
Renewal term			2 years
Expected lease proceeds			$ 1,000				$ 200	$ 200
Gross proceeds from common stock sale			$ 1,000
Common stock issued (in shares) | shares			1.8
Sale price (in dollars per shares) | $ / shares			$ 0.55
Volume weighted average stock price period			30 days
Termination notice period	150 days	120 days		120 days
Number of rights of first refusal | Right							1
Deferred revenue					$ 100		$ 100
Increase (Decrease) in Deferred Revenue							$ (125)		$ 74