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Long-Term Debt - Additional Information (Details) (USD $)
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12 Months Ended | 0 Months Ended | |||
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Dec. 31, 2014
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Oct. 24, 2012
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Jun. 10, 2011
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Dec. 31, 2013
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Nov. 08, 2013
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| Debt Instrument [Line Items] | |||||
| 8.50% Senior Notes | $ 900,000,000us-gaap_UnsecuredLongTermDebt | $ 900,000,000us-gaap_UnsecuredLongTermDebt | |||
| Senior notes interest rate | 8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage | ||||
| Restriction on payment of dividends | 60,000,000wti_DebtCovenantRestrictionRelatedToPaymentOfDividends | ||||
| Common stock and senior note repurchases | 100,000,000wti_DebtCovenantRestrictionRelatedToCommonStockAndSeniorNoteRepurchases | ||||
| Percentage of hedging contracts | 75.00%wti_DebtCovenantRestrictionRelatedToPercentageOfHedgingContract | ||||
| Adjustment to borrowing base | 0.25wti_BaseOfSeniorNotesForPotentialAdditionalBorrowingCapacity | ||||
| Revolving bank credit facility interest rate description | Borrowings under the revolving bank credit facility bear interest at the applicable London Interbank Offered Rate (“LIBOR”) plus a margin that varies from 1.75% to 2.75% depending on the level of total borrowings under the Credit Agreement, or an alternative base rate equal to the greater of (a) Prime Rate, (b) Federal Funds Rate plus 0.5%, and (c) LIBOR plus 1.0%, plus applicable margin ranging from 0.75% to 1.75%. | ||||
| Leverage ratio | 350.00%wti_LeverageRatio | ||||
| Current ratio | 100.00%wti_CurrentRatio | ||||
| Revolving bank credit facility | 447,000,000us-gaap_LongTermLineOfCredit | 290,000,000us-gaap_LongTermLineOfCredit | |||
| Revolving Bank Credit Facility Due November 2018 | |||||
| Debt Instrument [Line Items] | |||||
| Effective interest rate |
2.90%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_CreditFacilityAxis = us-gaap_RevolvingCreditFacilityMember |
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| London Interbank Offered Rate (LIBOR) | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |
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| Federal Funds Effective Swap Rate | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_VariableRateAxis = us-gaap_FederalFundsEffectiveSwapRateMember |
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| Minimum | |||||
| Debt Instrument [Line Items] | |||||
| Unused portion of the borrowing base commitment fee |
0.375%us-gaap_LineOfCreditFacilityCommitmentFeePercentage / us-gaap_RangeAxis = us-gaap_MinimumMember |
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| Minimum | London Interbank Offered Rate (LIBOR) | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
1.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |
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| Minimum | London Interbank Offered Rate Additional Applicable Margin | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
0.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = wti_LondonInterbankOfferedRateAdditionalApplicableMarginMember |
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| Maximum | |||||
| Debt Instrument [Line Items] | |||||
| Unused portion of the borrowing base commitment fee |
0.50%us-gaap_LineOfCreditFacilityCommitmentFeePercentage / us-gaap_RangeAxis = us-gaap_MaximumMember |
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| Maximum | London Interbank Offered Rate (LIBOR) | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
2.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |
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| Maximum | London Interbank Offered Rate Additional Applicable Margin | |||||
| Debt Instrument [Line Items] | |||||
| Debt instrument, basis spread on variable rate |
1.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = wti_LondonInterbankOfferedRateAdditionalApplicableMarginMember |
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| 8.50% Senior Notes, due June 2019 | |||||
| Debt Instrument [Line Items] | |||||
| 8.50% Senior Notes |
300,000,000us-gaap_UnsecuredLongTermDebt / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
600,000,000us-gaap_UnsecuredLongTermDebt / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Debt issuance, premium percentage |
106.00%wti_DebtInstrumentIssuancePremium / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Senior notes interest rate |
8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Senior notes maturity date | Jun. 15, 2019 | Jun. 15, 2019 | |||
| Net proceeds after fees and expenses |
312,000,000us-gaap_ProceedsFromIssuanceOfLongTermDebt / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
593,500,000us-gaap_ProceedsFromIssuanceOfLongTermDebt / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Effective interest rate |
8.40%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
7.70%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Senior notes payment terms | semi-annually in arrears on June 15 and December 15 of each year | ||||
| Estimated senior notes fair value |
594,000,000us-gaap_NotesPayableFairValueDisclosure / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
962,500,000us-gaap_NotesPayableFairValueDisclosure / us-gaap_DebtInstrumentAxis = wti_EightPointFivePercentSeniorNotesDueJuneTwoThousandNineteenMember |
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| Revolving Bank Credit Facility Due November 2018 | |||||
| Debt Instrument [Line Items] | |||||
| Revolving bank credit facility maximum lender commitment |
1,200,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
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| Credit agreement expiration date | Nov. 08, 2018 | ||||
| Revolving bank credit facility borrowing base |
750,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
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| Revolving bank credit facility |
447,000,000us-gaap_LongTermLineOfCredit / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
290,000,000us-gaap_LongTermLineOfCredit / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
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| Letters of credit outstanding |
600,000us-gaap_LettersOfCreditOutstandingAmount / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
400,000us-gaap_LettersOfCreditOutstandingAmount / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember |
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| Revolving Bank Credit Facility Due November 2018 | Letter of Credit | |||||
| Debt Instrument [Line Items] | |||||
| Revolving bank credit facility maximum lender commitment |
$ 300,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_DebtInstrumentAxis = wti_RevolvingBankCreditFacilityDueNovemberTwoThousandEighteenMember / us-gaap_ShortTermDebtTypeAxis = us-gaap_LetterOfCreditMember |
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- Definition
Percentage points added to the reference rate to compute the variable rate on the debt instrument. No definition available.
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- Definition
Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. No definition available.
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- Definition
The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used. No definition available.
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- Definition
Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Date the credit facility terminates, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The carrying value as of the balance sheet date of the noncurrent portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value portion of notes payable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
For additional net senior note borrowings, the percentage used to calculate the adjustment to the borrowing base, which is applied against the additional net senior note borrowings. No definition available.
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- Definition
Current ratio minimum as defined in the credit agreement. No definition available.
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- Definition
Debt covenant restrictions related to the maximum amount of common stock and net senior notes repurchases paid for a calendar year. No definition available.
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Debt covenant restrictions related to the maximum amount of dividend paid for a calendar year. No definition available.
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- Definition
Debt covenant restriction related to the percentage of estimate monthly production of oil and gas that can be hedged by derivative instruments measured on a monthly basis. No definition available.
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- Definition
Debt instrument issuance premium. No definition available.
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- Definition
Leverage ratio maximum as defined in the credit agreement. No definition available.
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