COMMITMENTS AND CONTINGENCIES - Lease Obligations and Purchase Commitments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Operating lease obligations (mining and surface rights)
2020	$ 2,926
2021	465
2022	470
2023	366
2024	335
Total	4,562
Reclamation costs
2020	2,548
2021	4,115
2022	4,637
2023	2,279
2024	549
Thereafter	27,637
Total	41,765
Construction
2020	1,249
Total	1,249
Exploration
2020	219
Total	219
Total
2020	6,942
2021	4,580
2022	5,107
2023	2,645
2024	884
Thereafter	27,637
Total	$ 47,795

Minimum amount of construction costs.

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Minimum amount of construction costs maturing in the next fiscal year following the latest fiscal year.

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Minimum amount of exploration costs.

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Minimum amount of exploration costs maturing in the next fiscal year following the latest fiscal year.

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No definition available.

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Amount of required minimum rental payments for leases for mining and surface rights having an initial or remaining non-cancelable letter-terms in excess of one year.

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No definition available.

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Amount of required minimum rental payments for operating leases for mining and surface rights having an initial or remaining non-cancelable lease term in excess of one year due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of required minimum rental payments for operating leases for mining and surface rights having an initial or remaining non-cancelable lease term in excess of one year due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases for mining and surface rights having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases for mining and surface rights having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases for mining and surface rights having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Minimum amount of reclamation costs.

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No definition available.

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Minimum amount of reclamation costs maturing in the fifth fiscal year following the latest fiscal year.

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No definition available.

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Minimum amount of reclamation costs maturing in the fourth fiscal year following the latest fiscal year.

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Minimum amount of reclamation costs maturing in the next fiscal year following the latest fiscal year.

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Minimum amount of reclamation costs maturing in the second fiscal year following the latest fiscal year.

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No definition available.

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Minimum amount of reclamation costs maturing in the third fiscal year following the latest fiscal year.

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Minimum amount of reclamation costs maturing after the fifth fiscal year.

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No definition available.

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Minimum amount of reclamation costs maturing in the next fiscal year following the latest fiscal year.

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- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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Amount of contractual obligation due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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No definition available.

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Amount of contractual obligation due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of contractual obligation due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of contractual obligation due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of contractual obligation due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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No definition available.

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Amount of contractual obligation due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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