Acquisitions - Paramount (Details) - Paramount Gold and Silver Corp. shares in Thousands	Apr. 17, 2015 USD ($) shares
Business Acquisition [Line Items]
Common stock conversion ratio	0.2016
Common shares issued (value)	$ 188,817,000
Cash	8,530,000
Transaction advisory fees and other acquisition costs	4,020,000
Total purchase price	201,367,000
Total assets acquired	307,193,000
Total liabilities assumed	105,826,000
Net assets acquired	201,367,000
Payments to acquire additional interests	$ 1,500,000
Ownership percentage acquired	4.90%
Common Stock
Business Acquisition [Line Items]
Common shares issued (in shares) | shares	32,667,327
Price per common share issued (UDS per share)	$ 5,780