Mining Properties (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Mineral Properties, Net [Abstract]
Mining Properties	$ 579,343	$ 547,998
Accumulated Amortization	(326,847)	(277,841)
Mineral Properties, Net Book	252,496	270,157
Bogoso/Prestea
Mineral Properties, Net [Abstract]
Mining Properties	126,469	119,700
Accumulated Amortization	(63,836)	(60,186)
Mineral Properties, Net Book	62,633	59,514
Bogoso Refactory
Mineral Properties, Net [Abstract]
Mining Properties	70,318	70,090
Accumulated Amortization	(39,121)	(34,839)
Mineral Properties, Net Book	31,197	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	336,804	314,801
Accumulated Amortization	(218,103)	(180,486)
Mineral Properties, Net Book	118,701	134,315
Other
Mineral Properties, Net [Abstract]
Mining Properties	29,657	27,312
Accumulated Amortization	(5,787)	(2,330)
Mineral Properties, Net Book	$ 23,870	$ 24,982