Mining Properties (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Mineral Properties, Net [Abstract]
Mining Properties	$ 568,203	$ 547,998
Accumulated Amortization	(308,853)	(277,841)
Mineral Properties, Net Book	259,350	270,157
Bogoso/Prestea
Mineral Properties, Net [Abstract]
Mining Properties	123,290	119,700
Accumulated Amortization	(63,049)	(60,186)
Mineral Properties, Net Book	60,241	59,514
Bogoso Refactory
Mineral Properties, Net [Abstract]
Mining Properties	70,309	70,090
Accumulated Amortization	(37,812)	(34,839)
Mineral Properties, Net Book	32,497	35,251
Mampon
Mineral Properties, Net [Abstract]
Mining Properties	16,095	16,095
Accumulated Amortization	0	0
Mineral Properties, Net Book	16,095	16,095
Wassa/HBB
Mineral Properties, Net [Abstract]
Mining Properties	328,914	314,801
Accumulated Amortization	(203,571)	(180,486)
Mineral Properties, Net Book	125,343	134,315
Other
Mineral Properties, Net [Abstract]
Mining Properties	29,595	27,312
Accumulated Amortization	(4,421)	(2,330)
Mineral Properties, Net Book	$ 25,174	$ 24,982