Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Long Lived Assets
Long Lived Assets, Total	$ 2,237,774				$ 2,675,811				$ 2,237,774	$ 2,675,811	$ 2,688,703
Revenues
Total Revenue	168,847	200,825	204,525	171,797	205,929	230,593	254,406	204,564	745,994	895,492	1,021,200
United States [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	384,626				608,051				384,626	608,051	515,096
Revenues
Total Revenue									268,023	243,379	208,517
Australia [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	25,668				29,408				25,668	29,408	33,999
Revenues
Total Revenue										18,848	18,737
Argentina [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	94,705				1,705				94,705	1,705	5,213
Revenues
Total Revenue										13,162	13,347
Bolivia [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	235,085				240,905				235,085	240,905	230,956
Revenues
Total Revenue										178,005	267,502
Mexico [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	1,487,228				1,795,677				1,487,228	1,795,677	1,903,374
Revenues
Total Revenue										442,098	513,097
Other Foreign Countries [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	$ 10,462				$ 65				$ 10,462	$ 65	$ 65