Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2025	Aug. 29, 2025
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of concession rights		$ 1.9
Estimated capital expenditures to commence mining operations		$ 91.2
Fair value measurement input description	Significant inputs include the estimated discount due to uncertainty of reinstatement (85%-95%), estimated capital expenditures necessary to commence mining operations ($91.2 million), discount rate (12.5%), estimated market multiple (0.65 x), and debt to true interest cost ratio (35%).
Estimated fair value measurement input		0.0065
Fair value discount rate		12.50%
Debt to true interest cost ratio		35.00%
Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated discount due to uncertainty reinstatement		95.00%
Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated discount due to uncertainty reinstatement		85.00%

$ 1.9

Fair value measurement input description

Significant inputs include the estimated discount due to uncertainty of reinstatement (85%-95%), estimated capital expenditures necessary to commence mining operations ($91.2 million), discount rate (12.5%), estimated market multiple (0.65 x), and debt to true interest cost ratio (35%).

Fair value discount rate

12.50%

Estimated discount due to uncertainty reinstatement

95.00%

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]