Acquisitions - JDS Silver (Details) - JDS Silver Holdings Ltd.	1 Months Ended
	Oct. 31, 2017 USD ($) shares
Business Acquisition [Line Items]
Common shares issued (in shares) | shares	4,200,000
Cash	$ 153,194,000
Contingent consideration, liability	47,705,000
Cash consideration	100,000,000.0
Purchase price	236,906,000
Assets:
Total assets acquired	328,450,000
Liabilities:
Total liabilities assumed	91,544,000
Total assets acquired	236,906,000
Common Stock
Business Acquisition [Line Items]
Common shares issued (value)	$ 36,007,000
Common shares issued (in shares) | shares	4,191,679
Price per common share issued (UDS per share)	$ 8,590