Contingencies - Schedule of Contingencies Reserve Balance (Details) - New Idria Mercury Mine [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Loss Contingencies [Line Items]
Beginning reserve balance		$ 12,082	$ 9,153	$ 11,855	$ 8,213
Changes in estimated environmental liability		300	1,500	3,800	2,800
Payments made	[1],[2]	(1,182)	(123)	(4,455)	(483)
Ending reserve balance	[3]	11,200	10,530	11,200	10,530
Beginning receivable balance		6,162	0	6,000	0
Changes in estimated probable insurance recovery		400	0	1,600	0
Insurance recovery reimbursements		(394)	0	(1,432)	0
Ending receivable balance	[4]	$ 6,168	$ 0	$ 6,168	$ 0

[1] (1) Payments made in 2022 were offset by insurance refunds of $0.3 million and $0.4 million in the three and nine months ended September 30, 2022, respectively. In the fourth quarter of 2022, Buckhorn reached an agreement with respect to certain insurance coverage related to defense costs for which recovery of accrued costs are recorded as a receivable to the extent such recovery is determined to be probable under this agreement.

[2] (4) Payments made for the nine months ended September 30, 2023 include a $1.9 million payment related to a settlement agreement with the EPA to resolve the past costs claim, which Buckhorn paid in the first quarter of 2023.

[3] (2) As of September 30, 2023, Buckhorn has a total ending reserve balance of $11.2 million related to the New Idria Mine, of which $7.7 million is classified in Other current liabilities and $3.5 million in Other liabilities (long-term).

[4] (3) As of September 30, 2023, Buckhorn has a total receivable balance related to the probable insurance recovery of $6.2 million, of which $3.2 million is classified in Accounts receivable and $3.0 million is classified in Other (long-term).