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equipmentus-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxisxbrldihttp://xbrl.org/2006/xbrldiwlfc_EnginesAndRelatedEquipmentMemberus-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxisexplicitMemberItemStandardhttp://www.willislease.com/20130630itemwlfc0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Engines and related equipment2true 3us-gaap_LongTermPurchaseCommitmentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Purchase commitments3false 4us-gaap_LongTermPurchaseCommitmentMinimumQuantityRequiredus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2truefalsefalse55falsefalsefalsexbrli:integerItemTypeintegerNumber of units of goods that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, 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truefalseD2006Q4_M10_SpareEnginesCFM567BAndCFM565BMember_CFMInternationalMemberhttp://www.sec.gov/CIK0001018164duration2006-10-01T00:00:002006-10-31T00:00:00falsefalseCFM56-7B and CFM56-5B spare enginesus-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxisxbrldihttp://xbrl.org/2006/xbrldiwlfc_SpareEnginesCFM567BAndCFM565BMemberus-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxisexplicitMemberfalsefalseCFMwlfc_LongTermPurchaseCommitmentBySupplierAxisxbrldihttp://xbrl.org/2006/xbrldiwlfc_CFMInternationalMemberwlfc_LongTermPurchaseCommitmentBySupplierAxisexplicitMemberItemStandardhttp://www.willislease.com/20130630itemwlfc0nanafalse0CFM56-7B and CFM56-5B spare engines | CFM7true 3us-gaap_LongTermPurchaseCommitmentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Purchase commitments8false 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option to purchase number of equipments additionally under the purchase agreement.No definition available.false256Option to purchase additional quantity11false 4wlfc_LongTermPurchaseCommitmentPurchaseOrderOutstandingNumberOfEngineswlfc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2truefalsefalse33falsefalsefalsexbrli:integerItemTypeintegerRepresents the number of engines outstanding to be purchased under the purchase commitment agreement.No definition available.false256Number of engines for which purchase orders are outstandingfalseCommitments, Contingencies, Guarantees and Indemnities (Details 2) (USD $)HundredThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.willislease.com/role/DisclosureCommitmentsContingenciesGuaranteesAndIndemnitiesDetails2211