Commitments and Contingencies - Additional Information (Details)		3 Months Ended
	May 17, 2017 USD ($)	Mar. 31, 2020 USD ($) claim	Dec. 31, 2019 USD ($)
Loss Contingencies
Purchased reserves	$ 94,400,000
Number of new claims | claim		0
Surety Bonds
Loss Contingencies
Surety bonds outstanding		$ 36,300,000
Reclamation Bonds
Loss Contingencies
Surety bonds outstanding		30,900,000
Other non-current assets
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		0	$ 0
Other long-term obligations
Loss Contingencies
Third party products claims liability under insurance in other long-term obligations		$ 1,000,000.0	$ 900,000
Pending Litigation
Loss Contingencies
Number of pending claims | claim		55