Commitments and Contigencies (Details Textual)	3 Months Ended
	Mar. 31, 2018 USD ($) t	Oct. 31, 2017 USD ($)	Oct. 02, 2014 USD ($)
Palmarejo gold production royalty
Business Acquisition [Line Items]
Production to be sold, percent	50.00%		50.00%
Price per ounce under agreement	$ 800		$ 800
Aggregate deposit to be received	20,000,000		$ 22,000,000
Palmarejo Gold Stream Agreement, Deferred Revenue Unamortized Balance	$ 14,300,000
JDS Silver Holdings Ltd.
Business Acquisition [Line Items]
Silvertip acquisition contingent consideration		$ 50,000,000
Long-term Purchase Commitment, Milestones	2
JDS Silver Holdings Ltd. | First Milestone
Business Acquisition [Line Items]
Silvertip acquisition contingent consideration		25,000,000
Sustained minim and milling per day (in tones) | t	1,000
JDS Silver Holdings Ltd. | Second Milestone
Business Acquisition [Line Items]
Silvertip acquisition contingent consideration		25,000,000.0
Maximum payment		$ 25,000,000
Tonnes of Resource Added | t	3,700,000
Amount of resource required (in tonnes) | t	300,000
Commitment amount per resource amount reached	$ 5,000,000
Minimum Resource Tonnes Milestone | t	2,500,000