Commitments and Contingencies - Purchase Obligations (Details) $ in Millions	Dec. 31, 2021 USD ($)
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligation	$ 32.6
Concentrate manufacturing
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligation	31.2
Ancillary supplies
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligation	$ 1.4