Contingencies - Schedule of Contingencies Reserve Balance (Details) - New Idria Mercury Mine [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2025		Dec. 31, 2024		Dec. 31, 2023
Loss Contingencies [Line Items]
Beginning reserve balance		$ 12,425	[1]	$ 13,182	[1]	$ 11,855
Changes in estimated environmental liability		2,500		3,100		6,500
Payments made	[2]	(2,421)		(3,857)		(5,173)
Ending reserve balance	[1]	12,504		12,425		13,182
Beginning receivable balance		8,404	[3]	7,245	[3]	6,000
Changes in estimated insurance recovery		2,300		3,300		3,300
Insurance recovery reimbursements		(2,372)		(2,141)		(2,055)
Ending receivable balance	[3]	$ 8,332		$ 8,404		$ 7,245

[1] (1) As of December 31, 2025, Buckhorn has a total ending reserve balance of $12.5 million related to the New Idria Mine, of which $8.8 million is classified in Other current liabilities, $3.3 million in Other liabilities (long-term) and $0.4 million in Accounts payable.

[2] (3) Payments made for the year ended December 31, 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 December 31, 2025, Buckhorn has a total receivable balance related to the probable insurance recovery of $8.3 million, of which $5.2 million is classified in Other accounts receivable and $3.1 million is classified in Other assets (long-term).