Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Long Lived Assets
Long Lived Assets, Total	$ 2,668,933		$ 2,688,704
Revenues
Total Revenue	204,564	199,624
UNITED STATES
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	520,403		515,096
Revenues
Total Revenue	29,135	62,372
AUSTRALIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	32,355		33,999
Revenues
Total Revenue	6,713	3,080
CHILE
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	65		65
ARGENTINA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	5,336		5,213
Revenues
Total Revenue	3,618	(314)
BOLIVIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	237,069		230,956
Revenues
Total Revenue	41,376	46,321
MEXICO
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	1,873,705		1,903,375
Revenues
Total Revenue	$ 123,722	$ 88,165