Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long Lived Assets
Entity Wide Disclosure on Geographic Areas Long Lived Assets in Entity's Country of Domicile and Foreign Countries	$ 729,103	$ 2,237,774
Revenues
Total Revenue	635,742	745,994	895,492
United States [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	275,594	384,626
Revenues
Total Revenue	260,728	268,023	243,379
Australia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	21,362	25,668
Revenues
Total Revenue	10,046	12,871	18,848
Argentina [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	10,970	94,705
Bolivia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	107,960	235,085
Revenues
Total Revenue	117,749	141,721	178,005
Mexico [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	298,101	1,487,228
Revenues
Total Revenue	245,493	324,040	442,098
Other Foreign Countries [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	15,116	10,462
Revenues
Total Revenue	1,726	(661)	13,162
Operating Segments [Member]
Revenues
Total Revenue		$ 745,994	$ 895,492