Reclamation (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Asset retirement obligation
Asset retirement obligation - Beginning			$ 57,454,000	$ 34,456,000
Accretion			4,205,000	2,277,000
Additions and changes in estimates	0	19,542,000
Settlements			(470,000)	(502,000)
Asset retirement obligation - Ending	61,189,000	55,773,000	61,189,000	55,773,000
Reclamation and Mine Closure (Textual) [Abstract]
Accrued reclamation liabilities	$ 500,000		$ 500,000		$ 1,000,000