Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Long Lived Assets
Entity Wide Disclosure on Geographic Areas Long Lived Assets in Entity's Country of Domicile and Foreign Countries	$ 2,211,454		$ 2,211,454		$ 2,237,774
Revenues
Total Revenue	164,562	204,525	324,195	376,322
United States [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	387,617		387,617		384,626
Revenues
Total Revenue	60,212	65,754	120,427	144,502
Australia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	23,858		23,858		25,668
Revenues
Total Revenue	1,971	3,479	4,860	6,462
Argentina [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	94,495		94,495		94,705
Bolivia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	228,606		228,606		235,085
Revenues
Total Revenue	29,078	49,236	56,632	82,377
Mexico [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	1,461,228		1,461,228		1,487,228
Revenues
Total Revenue	72,657	86,217	141,167	143,643
Other Foreign Countries [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	15,650		15,650		10,462
Revenues
Total Revenue	$ 644	$ (161)	$ 1,109	$ (662)