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Commitments and Contingencies - Additional Information (Details) | 6 Months Ended
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Jun. 30, 2021 USD ($)
Environmental Contingency |
Environmental accrual | $ 17,400,000
Expected period related to remediation expenditures for environmental contingencies period | 30 years
Potential increase in environmental costs | $ 11,600,000
Time period within which recorded estimate of its obligation may change | 12 months
Liability for conditional asset retirement obligations | $ 0
Minimum |
Environmental Contingency |
Period for final feasibility study | 4 months
Maximum |
Environmental Contingency |
Period for final feasibility study | 10 months

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