Asset Retirement Obligation and Reclamation Liabilities (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2012
Asset retirement and reclamation liabilities	$ 2,495,000
Summary of activity in the Velardena Operations ARO
ARO, Beginning balance	2,495,000
Accretion expense	147,000	$ 146,000
ARO, Ending balance	2,627,000
Velardena properties
Asset retirement and reclamation liabilities	2,448,000	2,380,000	$ 1,900,000
Amortization expense related to the ARC	2,000
Summary of activity in the Velardena Operations ARO
ARO, Beginning balance	2,448,000	2,380,000
Changes in estimates, and other	2,000	(128,000)
Accretion expense	156,000	146,000
ARO, Ending balance	$ 2,606,000	$ 2,398,000