Income and Mining Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 17,924	$ 16,084
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	1,336	1,030
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	4,854	810
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(704)	0
Unrecognized Tax Benefits	$ 23,410	$ 17,924