Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Long Lived Assets
Entity Wide Disclosure on Geographic Areas Long Lived Assets in Entity's Country of Domicile and Foreign Countries	$ 2,217,311		$ 2,237,774
Revenues
Total Revenue	159,633	171,797
United States [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	378,459		384,626
Revenues
Total Revenue	60,215	78,748
Australia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	24,715		25,668
Revenues
Total Revenue	2,889	2,983
Argentina [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	94,558		94,705
Bolivia [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	231,336		235,085
Revenues
Total Revenue	27,554	33,141
Mexico [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	1,472,092		1,487,228
Revenues
Total Revenue	68,511	57,426
Other Foreign Countries [Member]
Long Lived Assets
Long Lived Assets in Entity's Country of Domicile	16,151		10,462
Revenues
Total Revenue	$ 464	$ (501)