Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long Lived Assets
Long Lived Assets, Total				$ 2,790,317				$ 2,688,704	$ 2,688,704	$ 2,790,317	$ 2,779,093
Revenues
Total Revenue	343,575	231,090	199,624	207,586	118,564	101,018	88,289	246,911	1,021,200	515,457	300,361
United States [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile				488,104				515,160	515,160	488,104	401,320
Revenues
Total Revenue									208,517	77,951	45,473
Australia [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				37,147				33,999	33,999	37,147	39,136
Revenues
Total Revenue									18,737	10,618	5,807
Chile [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				14				0	0	14	25,628
Argentina [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				1,882				5,214	5,214	1,882	12,392
Revenues
Total Revenue									13,347	53,875	44,820
Bolivia [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				234,306				230,956	230,956	234,306	248,667
Revenues
Total Revenue									267,502	142,988	113,701
Mexico [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				2,028,864				1,903,375	1,903,375	2,028,864	2,051,950
Revenues
Total Revenue									513,097	230,025	90,560
Other Countries [Member]
Long Lived Assets
Long Lived Assets in Individual Foreign Countries				$ 0				$ 0	$ 0	$ 0	$ 0