XML 53 R43.htm IDEA: XBRL DOCUMENT
v3.20.2

Fair Value Measurements - Additional Information (Details) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2020 USD ($) engine | Sep. 30, 2019 USD ($) engine | Dec. 31, 2019 USD ($)
Derivative [Line Items] |  |  |
Fair value of notes receivable | $ 160.7 |  | $ 39.7
Fair value of notes payable | 1,333.3 |  | 1,262.6
Increase in interest expense | 1.3 | $ (0.5) |
Asset write-down | $ 14.4 | $ 11.3 |
Number of assets impaired | engine | 2 |  |
Remaining book value | $ 27.5 |  |
Number of assets previously impaired | engine | 14 | 11 |
Fair value, recurring | Fair value, inputs, Level 2 | Interest rate contract |  |  |
Derivative [Line Items] |  |  |
Notional amount, liability | $ 4.8 |  |
Assets at fair value |  |  | $ 1.7
Assets To Be Sold Or Parted Out |  |  |
Derivative [Line Items] |  |  |
Number of assets impaired | engine | 10 |  |

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of notes payable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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 + Details
Name: | us-gaap_NotesPayableFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_NotesReceivableFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Impaired Assets, Remaining Carrying Value + References No definition available. + Details
Name: | wlfc_ImpairedAssetsRemainingCarryingValue
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Increase (Decrease) in Asset Impairment Charges + References No definition available. + Details
Name: | wlfc_IncreaseDecreaseInAssetImpairmentCharges
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase (Decrease) In Interest Expense + References No definition available. + Details
Name: | wlfc_IncreaseDecreaseInInterestExpense
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number Of Assets Impaired + References No definition available. + Details
Name: | wlfc_NumberOfAssetsImpaired
Namespace Prefix: | wlfc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Assets Previously Impaired + References No definition available. + Details
Name: | wlfc_NumberOfAssetsPreviouslyImpaired
Namespace Prefix: | wlfc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=wlfc_AssetsToBeSoldOrPartedOutMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |