Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Long Lived Assets
Long Lived Assets, Total	$ 2,614,470		$ 2,614,470		$ 2,688,703
Revenues
Total Revenue	230,593	343,575	689,563	774,289
UNITED STATES
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	522,595		522,595		515,096
Revenues
Total Revenue	72,694	61,638	157,106	164,456
AUSTRALIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	29,865		29,865		33,999
Revenues
Total Revenue	4,132	6,205	16,077	15,835
CHILE
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	65		65		65
ARGENTINA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	1,772		1,772		5,213
Revenues
Total Revenue	4,933	6,037	12,700	10,492
BOLIVIA
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	241,890		241,890		230,956
Revenues
Total Revenue	46,192	102,820	140,951	204,739
MEXICO
Long Lived Assets
Long Lived Assets in Individual Foreign Countries	1,818,283		1,818,283		1,903,374
Revenues
Total Revenue	$ 102,642	$ 166,875	$ 362,729	$ 378,767