Document and Entity Information Aggregate par or stated value of issued common units. Common Units. Common units, 100,000,000 units authorized; zero and 19,069,662 issued at December 31, 2011 and 2010, respectively Accmulated Amortization Of Deferred Finance Costs And Other Assets Represents the amount of accumulated amortization of deferred financing costs and other assets on the reporting date by the entity. Deferred financing costs and other assets, accumulated amortization (in dollars) The maximum numbers of common units permitted to be issued by an entity's charter and bylaws. Common Units Authorized Common units, units authorized Common Units Issued Total number of common units of an entity that have been sold or granted to owners (includes common units that were issued, repurchased and remain in the treasury). These units represent capital invested by the firm's owners, and may be all or only a portion of the number of units authorized. Units issued include units outstanding and shares held in the treasury. Common units, units issued Stock Issued During Period Shares Share Based Compensation Forfeited And Cancelled Number of shares (or other type of equity) forfeited and cancelled during the period. Relinquishments of profit units (in shares) Accrete convertible preferred units to redemption amount Represents the accretion of preferred units to redemption amount. Accrete of Preferred Units to Redemption Cash Paid for [Abstract] Cash paid for: Deemed Payment and Termination of Notes Receivable Deemed payment and termination of notes receivable The value of deemed payment and termination of notes receivable in noncash investing or financing transactions. Notes receivable applied to FPSO purchase Notes Receivable Applied The fair value of notes receivable applied in noncash investing activities. Amendment Description Acquisition of FPSO and Notes Receivable Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accounts Payable and Accrued Liabilities Amendment Flag Acquisition of FPSO and Notes Receivable Notes Receivable Disclosure [Text Block] The entire disclosure for a significant property acquisition completed during the period. It also includes the disclosure for notes receivable applied to the purchase price. Jubilee Field Unitization Jubilee Field Unitization Disclosure [Text Block] Jubilee Field Unitization Entire disclosure on the Jubilee Field Unitization. Joint Interest Billings Joint Interest Billings Oil and Gas Joint Interest Billing Receivable Disclosure [Text Block] Represents all disclosure related to joint interest billings in one text block. Current Fiscal Year End Date Accounts Receivable, Net, Current Oil sales Document Period End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Document Type Additional Paid in Capital, Common Stock Additional paid-in capital Depreciation Depletion and depreciation Unrealized Gain (Loss) on Derivatives Derivative related activity Long-term receivables - joint interest billings, allowance (in dollars) Allowance for Doubtful Accounts Receivable, Noncurrent Amortization of Financing Costs Amortization - deferred financing costs Asset Retirement Obligation Disclosure [Text Block] Asset Retirement Obligations Asset Retirement Obligations, Noncurrent Asset retirement obligations CONSOLIDATED BALANCE SHEETS Basic (in dollars per share) Earnings Per Share, Basic Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Interest Interest Paid (Increase) decrease in inventories Increase (Decrease) in Inventories Increase in prepaid expenses and other Increase (Decrease) in Prepaid Expense and Other Assets Decrease in receivables Increase (Decrease) in Receivables Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Decrease in accounts payable Increase (Decrease) in Accounts Payable Increase (decrease) in accrued liabilities Increase (Decrease) in Accrued Liabilities Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Common Stock, Shares Authorized Common shares, authorized shares Common Stock, Shares, Issued Common shares, issued shares Common Stock, Value, Issued Common shares, $0.01 par value; 2,000,000,000 authorized shares; 390,865,673 and 390,530,946 issued at March 31, 2012 and December 31, 2011, respectively Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Condensed Financial Information of Parent Company Only Disclosure [Text Block] Schedule I Condensed Parent Company Financial Statements Convertible Preferred Stock [Member] Convertible preferred units Oil and Gas Production Expense Oil and gas production Liabilities, Current Total current liabilities Current liabilities: Liabilities, Current [Abstract] Debt Disclosure [Text Block] Debt Deferred income taxes Deferred Income Tax Expense (Benefit) Deferred Tax Assets, Net, Current Current deferred tax assets Deferred Tax Liabilities, Noncurrent Deferred tax liability Derivative Assets, Noncurrent Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Financial Instruments Derivative Liabilities, Current Derivatives Derivative Liabilities, Noncurrent Derivatives Diluted (in dollars per share) Earnings Per Share, Diluted Share-based Compensation Equity-based compensation Exploration Expense Exploration expenses Payments of Financing Costs Deferred financing costs Gain (Loss) on Derivative Instruments, Net, Pretax Derivatives, net Unrealized Gain (Loss) on Cash Flow Hedging Instruments Change in fair value of cash flow hedges Gains (Losses) on Extinguishment of Debt Loss on extinguishment of debt General and administrative General and Administrative Expense CONSOLIDATED STATEMENTS OF OPERATIONS Income Taxes Income Tax Disclosure [Text Block] Restricted cash Increase (Decrease) in Restricted Cash Interest Expense Interest expense Inventory, Net Inventories Liabilities and Equity Total liabilities and shareholders' equity Liabilities and shareholders' equity Liabilities and Equity [Abstract] Long-term Debt, Current Maturities Current maturities of long-term debt Long-term Debt, Excluding Current Maturities Long-term debt Loss on cash flow hedge included in operations Loss on cash flow hedge included in operations Loss on Cash Flow Hedge Ineffectiveness Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net loss Net loss Net loss Net Income (Loss) Attributable to Parent Net Income (Loss) Available to Common Stockholders, Basic Net loss attributable to common shareholders/unit holders Nonoperating Income (Expense) Other expenses, net Liabilities, Noncurrent Total long-term liabilities Liabilities, Noncurrent [Abstract] Long-term liabilities: Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization Oil and gas properties, accumulated depletion (in dollars) Oil and Gas Property, Successful Effort Method, Net Oil and gas properties, net of accumulated depletion of $174,315 and $135,622, respectively Revenues Total revenues and other income Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Derivatives, net Other Nonoperating Income Interest income Other property Payments to Acquire Other Property, Plant, and Equipment 401(k) Plan Pension and Other Postretirement Benefits Disclosure [Text Block] Preferred Stock, Shares Authorized Preference shares, authorized shares Preferred Stock, Shares Issued Preference shares, issued shares Other Preferred Stock Dividends and Adjustments Accretion to redemption value of convertible preferred units Preferred Stock, Par or Stated Value Per Share Preference shares, par value (in dollars per share) Net proceeds from issuance of units Proceeds from Issuance of Convertible Preferred Stock Proceeds from Issuance Initial Public Offering Net proceeds from the initial public offering Proceeds from Issuance of Long-term Debt Borrowings under long-term debt Property, Plant and Equipment, Net Property and equipment - net Property and Equipment Provision for Doubtful Accounts Doubtful accounts expense Oil and gas assets Payments to Acquire Oil and Gas Property and Equipment Payments for (Proceeds from) Investments Notes receivable Receivables: Receivables, Net, Current [Abstract] Repayments of Long-term Debt Payments on long-term debt Restricted Cash and Cash Equivalents, Current Restricted cash Results of Operations, Dry Hole Costs Unsuccessful well costs Unsuccessful well costs Retained Earnings (Accumulated Deficit) Accumulated deficit Revenue, Net [Abstract] Revenues and other income: Other Revenue, Net Other income Oil and Gas Sales Revenue Oil and gas revenue Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Schedule II Valuation and Qualifying Accounts Series B Convertible preferred units Series B Preferred Stock [Member] Series C Convertible preferred units Series C Preferred Stock [Member] Series A Convertible preferred units Series A Preferred Stock [Member] Significant Accounting Policies [Text Block] Accounting Policies CONSOLIDATED STATEMENTS OF CASH FLOWS CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY Shareholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Supplemental cash flow information Supplemental Cash Flow Information [Abstract] Income Taxes Paid Income taxes Temporary Equity [Abstract] Convertible preferred units, 100,000,000 units authorized: Assets, Current Total current assets Current assets: Assets, Current [Abstract] Treasury Stock Treasury Stock [Member] Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Common Units General Partner [Member] Common Shares Common Stock [Member] Property, Plant and Equipment Disclosure [Text Block] Property and Equipment Property and equipment: Property, Plant and Equipment, Net [Abstract] Assets Total assets Notes, Loans and Financing Receivable, Net, Current Notes Other Assets, Noncurrent [Abstract] Other assets: Deferred Finance Costs, Noncurrent, Net Deferred financing costs and other assets, net of accumulated amortization of $8,776 and $6,582, respectively Other Liabilities, Noncurrent Other long-term liabilities Deferred Tax Assets, Net, Noncurrent Long-term deferred tax assets Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Equity-based Compensation Scenario, Unspecified [Domain] Statement [Table] Statement, Scenario [Axis] Assets Assets [Abstract] Statement [Line Items] Statement Convertible Preferred Units Fair Value Measurements Fair Value Disclosures [Text Block] Temporary Equity, Carrying Amount Convertible preferred units Temporary Equity, Shares Authorized Convertible preferred units, units authorized Temporary Equity, Shares Issued Convertible preferred units, units issued Investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Class of Stock [Domain] Treasury Stock, Value Treasury stock, at cost, 650,937 and 649,818 shares at March 31, 2012 and December 31, 2011, respectively Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Accumulated other comprehensive income Increase (Decrease) in Shareholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Stockholders' Equity, Period Increase (Decrease) Net Income (Loss) Per Share Net loss per share attributable to common shareholders: Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Loss before income taxes Class of Stock [Axis] Common Stock, Par or Stated Value Per Share Common shares, par value (in dollars per share) Treasury Stock, Shares Treasury stock, shares Total shareholders' equity Balance Balance Stockholders' Equity Attributable to Parent Income Tax Expense (Benefit) Income tax expense (benefit) Income tax expense (benefit) Suspended Well Costs Disclosure [Text Block] Suspended Well Costs Preferred Stock, Value, Issued Preference shares, $0.01 par value; 200,000,000 authorized shares; zero issued at March 31, 2012 and December 31, 2011 Incentive from Lessor Leasehold improvement allowance Statement, Equity Components [Axis] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Deficit Retained Earnings [Member] Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income (Loss) [Member] Equity Component [Domain] Stock Issued During Period, Value, New Issues Common shares issued at initial public offering, net of offering costs Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Restricted stock forfeitures Stock Issued During Period, Shares, New Issues Common shares issued at initial public offering, net of offering costs (in shares) Stock Issued During Period, Shares, Period Increase (Decrease) Stock Issued During Period, Value, Conversion of Units Common and restricted shares issued upon corporate reorganization Stock Issued During Period, Shares, Conversion of Units Common and restricted shares issued upon corporate reorganization (in shares) Costs and Expenses [Abstract] Costs and expenses: Costs and Expenses Total costs and expenses Earnings Per Share, Pro Forma [Abstract] Shares, Issued Balance (in shares) Balance (in shares) Earnings Per Share [Text Block] Net Income (Loss) Per Share Weighted average number of shares used to compute net loss per share: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Depletion, depreciation and amortization Depreciation, Depletion and Amortization Oil and Gas Joint Interest Billing Receivables, Current Joint interest billings Oil and Gas Joint Interest Billing Receivables, Noncurrent Long-term receivables - joint interest billings, net of allowance of zero and $39.8 million, respectively Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Nature of Operations [Text Block] Organization Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued liabilities Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax, Portion Attributable to Parent Income tax benefit Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Equity-based compensation Capitalized Exploratory Well Cost, Charged to Expense Unsuccessful well costs Prepaid Expense and Other Assets, Current Prepaid expenses and other Net increase in cash and cash equivalents Net Cash Provided by (Used in) Continuing Operations Accounts Payable and Accrued Liabilities Organization Preferred Stock [Text Block] Convertible Preferred Units Commitments and Contingencies Stock Issued During Period, Value, Other Issuance of C1 units Issuance of C1 units (in shares) Stock Issued During Period, Shares, Other Asset Retirement Obligations Income Taxes Schedule I Condensed Parent Company Financial Statements Fair Value Measurements Subsequent Events Subsequent Events [Text Block] Debt Property, Plant and Equipment, Other, Accumulated Depreciation Other property, accumulated depreciation (in dollars) Property, Plant and Equipment, Other, Net Other property, net of accumulated depreciation of $8,953 and $8,068, respectively 401(k) Plan Derivative Financial Instruments Equity-based Compensation Suspended Well Costs Accounting Policies Subsequent Events Schedule II Valuation and Qualifying Accounts Other Other Noncash Income (Expense) Other Receivables, Net, Current Other Stock Issued During Period, Value, Share-based Compensation, Gross Issuance of profit units Stock Issued During Period, Value, Share-based Compensation, Forfeited Relinquishments of profit units Stock Issued During Period, Shares, Share-based Compensation, Gross Issuance of profit units (in shares) Noncash Investing and Financing Items [Abstract] Non-cash activities: Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax Reclassification adjustments for derivative losses included in net loss Business Combinations [Abstract] Acquisition of FPSO Business Combination Disclosure [Text Block] Acquisition of FPSO Acquisition of FPSO Disclosure [Text Block] The entire disclosure for acquisition of FPSO completed during the period. It also includes the disclosure for notes receivable applied to the purchase price. Acquisition of FPSO Restricted stock awards Stock Issued During Period, Value, Restricted Stock Award, Gross Restricted stock awards (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Gain Loss On Derivatives Net Derivative related activity The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures and forward contracts, held at each balance sheet date. Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax Reclassification adjustments for derivative losses included in net loss