Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes
Income before income taxes	$ 578,268,000	$ 75,954,000	$ 34,156,000
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	82,489,000	84,618,000	21,148,000
Deferred	216,409,000	82,380,000	80,036,000
Income tax expense	298,898,000	166,998,000	101,184,000
Reconciliation of income tax expense and the reported effective tax rate
Foreign income taxed at different rates	266,993,000	127,301,000	73,277,000
Change in valuation allowance	16,401,000	(4,065,000)	14,103,000
Non-deductible and other items	8,957,000	36,664,000	5,669,000
Tax shortfall related to equity-based compensation	6,547,000	7,098,000	8,135,000
Income tax expense	298,898,000	166,998,000	101,184,000
Effective tax rate (as a percent)	51.70%	219.90%	296.20%
Impact of losses incurred in jurisdictions in which company is not subject to taxes on effective tax rate	159,900,000	178,800,000	168,500,000
Deferred tax assets:
Foreign capitalized operating expenses	60,401,000	46,087,000
Foreign net operating losses	15,548,000	17,579,000
Equity compensation	36,711,000	28,112,000
Unrealized derivative losses		10,197,000
Other	20,657,000	9,582,000
Total deferred tax assets	133,317,000	111,557,000
Valuation allowance	(75,941,000)	(59,540,000)
Total deferred tax assets, net	57,376,000	52,017,000
Deferred tax liabilities:
Depletion, depreciation and amortization related to property and equipment	(322,895,000)	(186,333,000)
Unrealized derivative gains	(92,675,000)
Total deferred tax liabilities	(415,570,000)	(186,333,000)
Net deferred tax asset (liability)	(358,194,000)	(134,316,000)
Bermuda
Income Taxes
Income before income taxes	(31,787,000)	(26,492,000)	(11,651,000)
United States
Income Taxes
Income before income taxes	15,684,000	11,872,000	14,342,000
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	27,167,000	14,182,000	21,148,000
Deferred	(14,403,000)	(2,665,000)	(7,908,000)
Reconciliation of income tax expense and the reported effective tax rate
Effective tax rate (as a percent)	81.00%	97.00%	92.00%
Foreign-other
Income Taxes
Income before income taxes	594,371,000	90,574,000	31,465,000
Components of the provision for income taxes attributable to income (loss) before income taxes
Current	55,322,000	70,436,000
Deferred	230,812,000	85,045,000	87,944,000
Reconciliation of income tax expense and the reported effective tax rate
Effective tax rate (as a percent)	0.00%
Statutory tax rate (as a percent)	0.00%
Ghana
Reconciliation of income tax expense and the reported effective tax rate
Effective tax rate (as a percent)	36.00%	36.00%	36.00%
Cameroon
Deferred tax assets:
Total deferred tax assets			40,100,000
Valuation allowance			$ (40,100,000)