Income Taxes - Net Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Operating loss carryforwards
Net operating loss carryforwards	$ 330,200
Valuation allowance offsetting the deferred tax assets	110,510	$ 106,764
Unrecognized tax benefits would affect effective tax rate	0
Luxembourg and Chile
Operating loss carryforwards
Net operating loss carryforwards	38,000
Other non-U.S. Countries
Operating loss carryforwards
Net operating loss carryforwards	118,300
U.S
Operating loss carryforwards
Net operating loss carryforwards	58,600
Velardena properties
Operating loss carryforwards
Net operating loss carryforwards	92,400
Other Mexico Exploration Activities
Operating loss carryforwards
Net operating loss carryforwards	$ 22,900