Revenue Recognition (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue recognized in contract liability	$ 0.2	$ 0.2
Contract assets recognized	0.0
Thacker Pass
Disaggregation of Revenue [Line Items]
Reimbursable costs revenue	1.5	$ 0.1
Advance paid	3.5
Cost reimbursement, commercial mining milestone, fee	$ 4.7
Minimum
Disaggregation of Revenue [Line Items]
Primary term of contract	3 years
Maximum
Disaggregation of Revenue [Line Items]
Primary term of contract	5 years
Maximum | Thacker Pass
Disaggregation of Revenue [Line Items]
Capital expenditures	$ 50.0