2.4.0.84100 - Disclosure - Fair Value of Financial Instruments (Details)truefalsefalse1false USDfalsefalse$I2013Q2http://www.sec.gov/CIK0001018164instant2013-06-30T00:00:000001-01-01T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$I2012http://www.sec.gov/CIK0001018164instant2012-12-31T00:00:000001-01-01T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Fair value of financial instruments2false 2us-gaap_LongTermDebtus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalsepositiveTerseLabel1truefalsefalse744498000744498000USD$falsetruefalse2truefalsefalse696988000696988000USD$falsetruefalsexbrli:monetaryItemTypemonetaryCarrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 false2Carrying value on outstanding balance of notes payable3false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3false USDtruefalse$I2013Q2_FairValueInputsLevel3Memberhttp://www.sec.gov/CIK0001018164instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseLevel 3us-gaap_FairValueByFairValueHierarchyLevelAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FairValueInputsLevel3Memberus-gaap_FairValueByFairValueHierarchyLevelAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Level 34true 3us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Fair value of financial instruments5false 4us-gaap_NotesPayableFairValueDisclosureus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse734900000734900000USD$falsetruefalse2truefalsefalse697300000697300000USD$falsetruefalsexbrli:monetaryItemTypemonetaryThis element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents notes payable as of the balance sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20,22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false2Fair value of notes payablefalseFair Value of Financial Instruments (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.willislease.com/role/DisclosureFairValueOfFinancialInstrumentsDetails25