Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Goodwill [Line Items]
Goodwill impairment	$ (33,355)	$ 0	$ (33,355)	$ 0
Goodwill balance	2,280		2,280		$ 35,634
Owned and Operated Mines [Member]
Goodwill [Line Items]
Goodwill balance	2,300		2,300
Cordero Rojo Complex [Member]
Goodwill [Line Items]
Goodwill impairment	(33,400)
Goodwill balance	$ 0		$ 0