Inventories (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2012 oz	Dec. 31, 2011 oz
Inventory, Net [Abstract]
Stockpiled ore	$ 29,557,000	$ 16,773,000
In-process	10,716,000	8,912,000
Materials and supplies	47,836,000	48,612,000
Finished goods	0	0
Total	88,109,000	74,297,000
Recoverable ounces of gold	59,000	48,000
Material and supplies inventory written off	200,000	1,400,000
Net realizable value adjustments recorded at Bogoso	$ 100,000	$ 1,700,000