Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Income Taxes
Income tax expense (benefit)	$ 22,177	$ (2,022)
Effective tax rate (as a percent)	333.00%	3.00%
Income (loss) before income taxes	$ (6,664)	$ (61,015)
Components of the provision for income taxes attributable to income (loss) before income taxes
Deferred	22,133	(1,951)
Bermuda
Income Taxes
Income (loss) before income taxes	$ (16,181)	$ (15,797)
United States
Income Taxes
Effective tax rate (as a percent)	21.00%	108.00%
Income (loss) before income taxes	$ 1,412	$ 2,096
Foreign-other
Income Taxes
Effective tax rate (as a percent)	0.00%
Statutory tax rate (as a percent)	0.00%
Income (loss) before income taxes	$ 8,105	$ (47,314)
Ghana
Income Taxes
Effective tax rate (as a percent)	35.00%	35.00%

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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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