Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Long Lived Assets
Long Lived Assets, Total	$ 3,018,022		$ 3,018,022		$ 2,675,811
Revenues
Total Revenue	204,525	254,406	376,322	458,970
UNITED STATES
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	503,105		503,105		514,687
Revenues
Total Revenue	65,754	55,277	144,502	84,411
AUSTRALIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	27,364		27,364		29,408
Revenues
Total Revenue	3,479	5,232	6,462	11,946
ARGENTINA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	94,964		94,964		95,134
Revenues
Total Revenue	(161)	4,149	(662)	7,767
BOLIVIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	235,781		235,781		240,905
Revenues
Total Revenue	49,236	53,383	82,377	94,759
MEXICO
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	2,156,808		2,156,808		1,795,677
Revenues
Total Revenue	$ 86,217	$ 136,365	$ 143,643	$ 260,087