Contingencies - Schedule of Contingencies Reserve Balance (Parenthetical) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023		Jun. 30, 2024		Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
EPA Notice Letter [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies revision in estimates	$ 1,900
New Idria Mercury Mine [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 12,082	[1]	$ 12,492	[1]	$ 12,315	$ 13,182	$ 10,724	$ 11,855
Estimated Insurance Recoveries			7,100
New Idria Mercury Mine [Member] | Other Current Liabilities [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 6,400
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]			Other Accrued Liabilities, Current
New Idria Mercury Mine [Member] | Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 6,100
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]			Other Liabilities, Noncurrent
New Idria Mercury Mine [Member] | Accounts Receivable [Member]
Loss Contingencies [Line Items]
Estimated Insurance Recoveries			$ 2,900
New Idria Mercury Mine [Member] | Other Noncurrent Assets [Member]
Loss Contingencies [Line Items]
Estimated Insurance Recoveries			$ 4,200

[1] (1) As of June 30, 2024, Buckhorn has a total ending reserve balance of $12.5 million related to the New Idria Mine, of which $6.4 million is classified in Other current liabilities and $6.1 million in Other liabilities (long-term).