Contingencies - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended		120 Months Ended	254 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2018	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2016	Sep. 30, 2021	Feb. 14, 2014	Dec. 31, 2021
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Revision in Estimates						$ 2,000,000.0
Other current liabilities	$ 20,758,000			$ 20,758,000						$ 19,628,000
Other liabilities	13,863,000			13,863,000						$ 13,086,000
New Idria Mercury Mine [Member]
Loss Contingencies [Line Items]
Financial assurance required to be provided to EPA to secure performance			$ 2,000,000
New Almaden Mine (Formerly Referred to as Guadalupe River Watershed) [Member] | Natural Resource Damage Claim [Member]
Loss Contingencies [Line Items]
Total reserve	1,500,000			1,500,000
Other current liabilities	300,000			300,000
Other liabilities	1,200,000			1,200,000
Expense recognized	0	$ 0
Revised estimated project total costs, Low Estimate							$ 3,300,000
Revised estimated project total costs, High Estimate							$ 4,400,000
Pending Litigation [Member] | New Idria Mercury Mine [Member] | EPA Notice Letter [Member]
Loss Contingencies [Line Items]
Loss contingencies, payments				3,200,000
Accrual for Environmental Loss Contingencies, Charges to Expense for New Losses	600,000	0		1,300,000	$ 0			$ 12,400,000	$ 1,600,000
Loss contingency, Loss in period	600,000	$ 0		1,300,000	$ 0			$ 12,400,000	$ 1,600,000
Total reserve	9,200,000			9,200,000
Other current liabilities	1,100,000			1,100,000
Other liabilities	$ 8,100,000			$ 8,100,000