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The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A3 -Appendix A Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section E Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 false 6 Begining balance, shares at Dec. 31, 2008 3 us-gaap_SharesIssued us-gaap true na instant No definition available. false false false true false false false false true false false periodstartlabel instant 2009-01-01T00:00:00 0001-01-01T00:00:00 false 1 false true false false 42582000 42582 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury. No authoritative reference available. false 7 Net income (loss) 3 us-gaap_NetIncomeLoss us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false true false false -136922000 -136922 true false false 5 false false false false 0 0 true false false 6 false true false false -136922000 -136922 true false false 7 false true false false -136922000 -136922 false false false xbrli:monetaryItemType monetary The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph d Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A7 -Appendix A Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 20 -Article 9 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 10, 15 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 87-21 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28, 29, 30 false 8 Change in derivative fair values, net of taxes of $7,799 3 us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 13348000 13348 true false false 6 false true false false 13348000 13348 true false false 7 false true false false 13348000 13348 false false false xbrli:monetaryItemType monetary Change in accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges, net of tax effect. The after tax effect change includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 17, 20 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 121 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 24 -Subparagraph b Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 46 false 9 Realized gain on settled derivative contracts, net of taxes of $4,933 3 us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeNet us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -8517000 -8517 true false false 6 false true false false -8517000 -8517 true false false 7 false true false false -8517000 -8517 false false false xbrli:monetaryItemType monetary The amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph b false 10 Ineffectiveness loss on hedging activities, net of taxes of $8,433 3 us-gaap_DerivativeNetHedgeIneffectivenessGainLoss us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 14433000 14433 true false false 6 false true false false 14433000 14433 true false false 7 false true false false 14433000 14433 false false false xbrli:monetaryItemType monetary The portion of a hedge deemed to be ineffective that is reflected in current period results of operations. No authoritative reference available. false 11 OCI amortization on de-designated hedges, net of taxes of $2,272 and $5,626 for six months ended June 30, 2009 and 2010 respectively 3 us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax us-gaap true debit duration No definition available. false false false false false false false false false false true negatedtotal false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -4576000 -4576 true false false 6 false true false false -4576000 -4576 true false false 7 false true false false -4576000 -4576 false false false xbrli:monetaryItemType monetary Net of tax effect of the reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 18, 19 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 24 -Subparagraph b Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 31, 46 true 12 Total comprehensive income 3 us-gaap_ComprehensiveIncomeNetOfTax us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false true false false -122234000 -122234 true false false 7 false false false false 0 0 false false false xbrli:monetaryItemType monetary The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A5 -Appendix A Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 30 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 8, 9, 10, 11, 12, 13, 14 true 13 Issuance of 6.25% convertible perpetual preferred stock 3 wll_IssuanceOfConvertiblePerpetualPreferredStock wll false credit duration Issuance of convertible perpetual preferred stock. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false true false false 3000 3 true false false 3 false true false false 334559000 334559 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false 334562000 334562 false false false xbrli:monetaryItemType monetary Issuance of convertible perpetual preferred stock. No authoritative reference available. false 14 Issuance of 6.25% convertible perpetual preferred stock, shares 3 wll_IssuanceOfConvertiblePerpetualPreferredStockShares wll false na duration Issuance of convertible perpetual preferred stock. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false true false false 3450000 3450 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Issuance of convertible perpetual preferred stock. No authoritative reference available. false 15 Issuance of stock, secondary offering 3 us-gaap_StockIssuedDuringPeriodValueNewIssues us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 8000 8 true false false 2 false false false false 0 0 true false false 3 false true false false 234745000 234745 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false 234753000 234753 false false false xbrli:monetaryItemType monetary Value of new stock issued during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 false 16 Issuance of stock, secondary offering, shares 3 us-gaap_StockIssuedDuringPeriodSharesNewIssues us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 8450000 8450 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Number of new stock issued during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 false 17 Restricted stock issued 3 us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 364000 364 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 4, 5 false 18 Restricted stock forfeited 3 us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -3000 -3 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Number of shares related to Restricted Stock Award forfeited during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 4, 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 false 19 Restricted stock used for tax withholdings 3 wll_RestrictedStockUsedForTaxWithholdingsValue wll false debit duration Restricted stock used for tax withholdings. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false true false false -654000 -654 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false -654000 -654 false false false xbrli:monetaryItemType monetary Restricted stock used for tax withholdings. No authoritative reference available. false 20 Restricted stock used for tax withholdings, shares 3 wll_RestrictedStockUsedForTaxWithholdingsShares wll false na duration Restricted stock used for tax withholdings Shares. false false false false false false false false false false false verboselabel false 1 false true false false -27000 -27 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Restricted stock used for tax withholdings Shares. No authoritative reference available. false 21 Tax effect from restricted stock vesting 3 us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false true false false -515000 -515 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false -515000 -515 false false false xbrli:monetaryItemType monetary Tax benefit associated with any share-based compensation plan other than an employee stock ownership plan (ESOP). The tax benefit results from the deduction by the entity on its tax return for an award of stock that exceeds the cumulative compensation cost for common stock or preferred stock recognized for financial reporting. Includes any resulting tax benefit that exceeds the previously recognized deferred tax asset (excess tax benefits). 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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 39 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A91 false 24 Ending balance at Jun. 30, 2009 3 us-gaap_StockholdersEquity us-gaap true credit instant No definition available. false false false true false false false false false true false periodendlabel instant 2009-06-30T00:00:00 0001-01-01T00:00:00 false 1 false true false false 51000 51 true false false 2 false true false false 3000 3 true false false 3 false true false false 1542022000 1542022 true false false 4 false true false false 683245000 683245 true false false 5 false true false false 31959000 31959 true false false 6 false false false false 0 0 true false false 7 false true false false 2257280000 2257280 false false false xbrli:monetaryItemType monetary Total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. 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No authoritative reference available. false 5 Begining balance at Dec. 31, 2009 3 us-gaap_StockholdersEquity us-gaap true credit instant No definition available. false false false true false false false false true false false periodstartlabel instant 2010-01-01T00:00:00 0001-01-01T00:00:00 false 1 false true false false 51000 51 true false false 2 false true false false 3000 3 true false false 3 false true false false 1546635000 1546635 true false false 4 false true false false 702983000 702983 true false false 5 false true false false 20413000 20413 true false false 6 false false false false 0 0 true false false 7 false true false false 2270085000 2270085 false false false xbrli:monetaryItemType monetary Total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. 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No authoritative reference available. false 7 Net income (loss) 3 us-gaap_NetIncomeLoss us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false true false false 211928000 211928 true false false 5 false false false false 0 0 true false false 6 false true false false 211928000 211928 true false false 7 false true false false 211928000 211928 false false false xbrli:monetaryItemType monetary The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph d Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A7 -Appendix A Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 20 -Article 9 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 10, 15 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 87-21 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28, 29, 30 false 11 OCI amortization on de-designated hedges, net of taxes of $2,272 and $5,626 for six months ended June 30, 2009 and 2010 respectively 3 us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax us-gaap true debit duration No definition available. false false false false false false false false false false true negatedtotal false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -9633000 -9633 true false false 6 false true false false -9633000 -9633 true false false 7 false true false false -9633000 -9633 false false false xbrli:monetaryItemType monetary Net of tax effect of the reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 18, 19 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 24 -Subparagraph b Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 31, 46 true 12 Total comprehensive income 3 us-gaap_ComprehensiveIncomeNetOfTax us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false true false false 202295000 202295 true false false 7 false false false false 0 0 false false false xbrli:monetaryItemType monetary The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A5 -Appendix A Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 30 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 8, 9, 10, 11, 12, 13, 14 true 17 Restricted stock issued 3 us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 161000 161 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 4, 5 false 18 Restricted stock forfeited 3 us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -6000 -6 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Number of shares related to Restricted Stock Award forfeited during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 4, 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 false 19 Restricted stock used for tax withholdings 3 wll_RestrictedStockUsedForTaxWithholdingsValue wll false debit duration Restricted stock used for tax withholdings. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false true false false -5655000 -5655 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false -5655000 -5655 false false false xbrli:monetaryItemType monetary Restricted stock used for tax withholdings. No authoritative reference available. false 20 Restricted stock used for tax withholdings, shares 3 wll_RestrictedStockUsedForTaxWithholdingsShares wll false na duration Restricted stock used for tax withholdings Shares. false false false false false false false false false false false verboselabel false 1 false true false false -77000 -77 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Restricted stock used for tax withholdings Shares. No authoritative reference available. false 22 Stock-based compensation 3 us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false true false false 4390000 4390 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false 4390000 4390 false false false xbrli:monetaryItemType monetary This element represents the amount of recognized share-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 39 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A91 false 23 Preferred stock dividends paid 3 us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 true false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false true false false -10781000 -10781 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false -10781000 -10781 false false false xbrli:monetaryItemType monetary The cash outflow for the return on capital for preferred shareholders. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a false 24 Ending balance at Jun. 30, 2010 3 us-gaap_StockholdersEquity us-gaap true credit instant No definition available. false false false true false false false false false true false periodendlabel instant 2010-06-30T00:00:00 0001-01-01T00:00:00 false 1 true true false false 51000 51 true false false 2 true true false false 3000 3 true false false 3 true true false false 1545370000 1545370 true false false 4 true true false false 904130000 904130 true false false 5 true true false false 10780000 10780 true false false 6 false false false false 0 0 true false false 7 true true false false 2460334000 2460334 false false false xbrli:monetaryItemType monetary Total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A3 -Appendix A Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section E Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 false 25 Ending balance, shares at Jun. 30, 2010 3 us-gaap_SharesIssued us-gaap true na instant No definition available. false false false true false false false false false true false periodendlabel instant 2010-06-30T00:00:00 0001-01-01T00:00:00 false 1 false true false false 51442000 51442 true false false 2 false true false false 3450000 3450 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 false false false xbrli:sharesItemType shares Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury. No authoritative reference available. false 7 33 false Thousands Thousands UnKnown false true