Asset Retirement Obligation and Reclamation Liabilities (Details) - USD ($)	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2012
Asset retirement and reclamation liabilities (Note 12)	$ 3,209,000
Summary of activity in the Velardena Operations ARO
ARO, Beginning balance	3,166,000
Accretion expense	131,000	$ 121,000
ARO, Ending balance	3,209,000
Velardena Properties
Asset retirement and reclamation liabilities (Note 12)	3,201,000	3,028,000	$ 1,900,000
Summary of activity in the Velardena Operations ARO
ARO, Beginning balance	3,156,000	2,825,000
Changes in estimates, and other	(86,000)	82,000
Accretion expense	131,000	121,000
ARO, Ending balance	3,201,000	3,028,000
Rodeo Project
Environmental costs	$ 0	$ 0

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of environmental remediation costs capitalized. These expenditures may relate to long-lived improvements in operating facilities.

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