1.0.0.3 false CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY AND COMPREHENSIVE INCOME (PARENTHETICAL) (USD $) In Millions, except Per Share data false 1 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 3 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 2 CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY AND COMPREHENSIVE INCOME 0 us-gaap_StatementOfStockholdersEquityAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 3 Change in pension and postretirement benefit plans, tax 1 us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansTaxPortionAttributableToParent us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 44200000 44.2 false false 2 true true 32300000 32.3 false false 3 true true -9700000 -9.7 false false No definition available. No authoritative reference available. false 4 Change in unrealized gain (loss) on hedges, tax 1 us-gaap_OtherComprehensiveIncomeDerivativesQualifyingAsHedgesTaxPortionAttributableToParent us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -400000 -0.4 false false 2 false true 4500000 4.5 false false 3 false true -4300000 -4.3 false false No definition available. No authoritative reference available. false 5 Service cost, interest cost, and expected return on plan assets, tax 1 wlt_EffectOnRetainedEarningsAccumulatedDeficitDueToChangeInMeasurementDateTax wlt false debit duration monetary Tax provision or (benefit) related to the adjustment decreasing (increasing) retained earnings due to a change in the... false false false false false false false false false 1 false false 0 0 false false 2 false true -3000000 -3.0 false false 3 false false 0 0 false false Tax provision or (benefit) related to the adjustment decreasing (increasing) retained earnings due to a change in the measurement date for a defined benefit pension and other postretirement plan in the initial application of the measurement provision of FAS 158. No authoritative reference available. false 6 Amortization of prior service cost and actuarial gain/loss, tax 1 wlt_EffectOnOtherComprehensiveIncomeLossDueToChangeInMeasurementDateTax wlt false debit duration monetary Tax provision or (benefit) related to the adjustment increasing (decreasing) other comprehensive income due to a change in... false false false false false false false false false 1 false false 0 0 false false 2 true true 500000 0.5 false false 3 false false 0 0 false false Tax provision or (benefit) related to the adjustment increasing (decreasing) other comprehensive income due to a change in the measurement date for a defined benefit pension and other postretirement plan in the initial application of the measurement provisions of FAS 158. No authoritative reference available. false 7 Dividends paid (in dollars per share) 1 us-gaap_CommonStockDividendsPerShareCashPaid us-gaap true na duration decimal No definition available. false false false false false false false false true 1 true true 0.40 0.40 false false 2 true true 0.30 0.30 false false 3 true true 0.20 0.20 false false No definition available. No authoritative reference available. false false 3 6 false HundredThousands UnKnown NoRounding false true