Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Income tax expense (benefit)	$ (10,784)	$ 155,272	$ 298,898
Income (loss) before income taxes	$ (294,564)	$ 85,436	$ 578,268
Effective tax rate (as a percent)	4.00%	182.00%	52.00%
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	$ 12,777	$ 44,486	$ 82,489
Deferred	(23,561)	110,786	216,409
Reconciliation of income tax expense and the reported effective tax rate
Foreign income (loss) taxed at different rates	(57,898)	94,184	266,993
Change in valuation allowance and the expiration of fully valued deferred tax assets	29,263	40,600	16,401
Non-deductible and other items	12,347	1,885	8,957
Tax shortfall related to equity-based compensation	5,504	18,603	6,547
Impact of losses incurred in jurisdictions in which company is not subject to taxes on effective tax rate	121,400	153,500	159,900
Bermuda
Income Taxes
Income (loss) before income taxes	(63,749)	(62,372)	(31,787)
United States
Income Taxes
Income (loss) before income taxes	$ 5,083	$ 10,652	$ 15,684
Effective tax rate (as a percent)	179.00%	220.00%	81.00%
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	$ 12,675	$ 15,199	$ 27,167
Deferred	(3,594)	8,241	(14,403)
Foreign-other
Income Taxes
Income (loss) before income taxes	$ (235,898)	137,156	594,371
Effective tax rate (as a percent)	0.00%
Statutory tax rate (as a percent)	0.00%
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	$ 102	29,287	55,322
Deferred	$ (19,967)	$ 102,545	$ 230,812
Ghana
Income Taxes
Effective tax rate (as a percent)	23.00%	35.00%	36.00%
Parent company
Income Taxes
Income (loss) before income taxes	$ (283,780)	$ (69,836)	$ 279,370