Segment Reporting (Details 2) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	$ 231,090	$ 101,018	$ 430,714	$ 189,307
ARGENTINA
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	4,769	9,187	4,455	24,207
AUSTRALIA
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	6,550	3,306	9,630	5,618
BOLIVIA
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	55,598	31,275	101,919	45,867
MEXICO
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	123,727	44,834	211,892	90,448
UNITED STATES
Entity-Wide Disclosure on Geographic Areas, Revenue from External Customers Attributed to Individual Foreign Countries [Line Items]
Total Revenue	$ 40,446	$ 12,416	$ 102,818	$ 23,167