Income Taxes (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Current expense:
Canada	$ 0	$ 0
Foreign	10,306,000	0
Deferred tax expense:
Canada	0	0
Foreign	(3,173,000)	12,531,000
Total expense	7,133,000	12,531,000
Income taxes paid		200,000
Tax expense related to the activity of the first six monthsof 2012		2,900,000
GHANA
Deferred tax expense:
Income taxes paid	8,300,000
Ghana statutory tax rate		35.00%	25.00%
Impact on deferred tax expense		$ 9,600,000