Income Taxes Schedule of Tax Pool and Loss Carryover Expirations (Details) (Tax Pool and Loss Carryovers [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Canada
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	$ 137,108
Canada | 2013
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Canada | 2014
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Canada | 2015
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	3,831
Canada | 2016
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Canada | 2026
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	15,800
Canada | 2027
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	16,096
Canada | 2028
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	14,468
Canada | 2029
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	22,248
Canada | 2030
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	20,421
Canada | 2031
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	38,314
Canada | Indefinite
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	5,930
Ghana
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	536,950
Ghana | 2013
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	46,294
Ghana | 2014
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2015
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2016
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	31,233
Ghana | 2026
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2027
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2028
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2029
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2030
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | 2031
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	0
Ghana | Indefinite
Tax Credit Carryforward [Line Items]
Total tax pool and loss carryovers	$ 459,423