Income Taxes (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Income Taxes
Total deferred tax assets	$ 165,293	$ 133,317
Valuation allowance	116,541	$ 75,941
Foreign net operating loss carryforwards	53,600
Foreign net operating loss carryforwards expiring in 2015	9,400
Foreign net operating loss carryforwards expiring in 2016	35,500
Foreign net operating loss carryforwards expiring in 2019	1,500
Foreign net operating loss carryforwards expiring in 2021	600
Foreign net operating loss carryforwards expiring in 2022	500
Foreign net operating loss carryforwards not expiring	6,100
Morocco
Income Taxes
Total deferred tax assets	$ 57,600
Tax rate applicable relating to tax holiday (as a percent)	0.00%
Period of income tax holiday from date of first production	10 years
Applicable foreign statutory tax rate (as a percent)	30.00%
Cameroon
Income Taxes
Total deferred tax assets			$ 40,100
Ireland, Mauritania, Morocco, Senegal and Suriname
Income Taxes
Net change in valuation allowance on deferred tax assets	$ 40,600