Sales (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Product Information [Line Items]
Revenues from by-product sales		$ 5,000,000	$ 6,900,000	$ 18,700,000	$ 22,200,000
Term of refining agreement	5 years
Period after which refining agreement may be terminated	4 years
Other revenue		100,000	5,490,000	$ 300,000	$ 5,725,000
Metal Acquired in Open Market and Resold to Third Parties [Member]
Product Information [Line Items]
Other revenue		$ 0	$ 5,300,000