Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		12 Months Ended
	May 29, 2020	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Cash paid for interest		$ 5,366	$ 10,239
Significant non-cash financing and investing activities:
Write-off of Seller's debt issuance costs		8,202	0
Plant, equipment, and mine development additions included in accounts payable		1,229	2,458
Private Warrants transferred to Public Warrants		581	0
Accrual of deferred financing and equity issuance costs		94	1,025
1.5 Lien Notes to common stock
Significant non-cash financing and investing activities:
Debt converted	$ 145,700	160,254	0
1.25 Lien Notes for Subordinated Notes
Significant non-cash financing and investing activities:
Debt converted	80,000	80,000	0
1.25 Lien Notes to common stock
Significant non-cash financing and investing activities:
Debt converted	$ 48,500	$ 48,459	$ 0