XML 60 R38.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Organization and Summary of Significant Accounting Policies (Organization and Revenue Recognition) (Details) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Aug. 04, 2017 USD ($) engine item | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) engine
Organizations [Line Items] |  |  |
Number of engines | engine |  |  | 393
Total |  | $ 1,103,743 | $ 913,703
Number of business days to pay interest | 5 days |  |
Maturity term | 10 years |  |
Maintenance Reserves |  | 75,889 | 71,602
Security Deposit Liability |  | 25,302 | 21,417
Revenue Recognition |  |  |
Lease rent to be received, more than 30 days past due |  | 8,300 |
Maintenance reserve payments to be received, more than 30 days past due |  | $ 5,600 |
Minimum number of days for which lease rent and maintenance reserve payments are past due |  | 30 days |
Other Revenue, Net |  | $ 1,300 | $ 4,000
Credit facility at a floating rate of interest of LIBOR plus 2.75%, secured by engines |  |  |
Organizations [Line Items] |  |  |
Total |  | 491,000 |
WEST III Series A 2017-1 term notes payable at a fixed rate of interest of 4.69%, maturing in August 2042. Secured by engines |  |  |
Organizations [Line Items] |  |  |
Total |  | 289,295 |
WEST III Series B 2017-1 term notes payable at a fixed rate of interest of 6.36%, maturing in August 2042. Secured by engines |  |  |
Organizations [Line Items] |  |  |
Total |  | 41,370 |
WEST III |  |  |
Organizations [Line Items] |  |  |
Number of series notes | item | 2 |  |
Maintenance Reserves |  | 10,000 |
Security Deposit Liability |  | $ 1,000 |
WEST III | Revolving credit facility |  |  |
Organizations [Line Items] |  |  |
Number of engines | engine | 56 |  |
WEST III | WEST III Series A 2017-1 term notes payable at a fixed rate of interest of 4.69%, maturing in August 2042. Secured by engines |  |  |
Organizations [Line Items] |  |  |
Aggregate principal amount | $ 293,700 |  |
Fixed rate (as a percent) |  | 4.69% |
WEST III | WEST III Series B 2017-1 term notes payable at a fixed rate of interest of 6.36%, maturing in August 2042. Secured by engines |  |  |
Organizations [Line Items] |  |  |
Aggregate principal amount | $ 42,000 |  |
Fixed rate (as a percent) |  | 6.36% |
WOLF |  |  |
Organizations [Line Items] |  |  |
Previously held interest (as a percent) |  | 50.00% |
Acquisition of the remaining outstanding shares (as a percent) |  | 100.00% |

X
- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination. + References No definition available. + Details
Name: | us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: 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 2: 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 3: 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 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after sales adjustments, returns, allowances, and discounts, of revenue classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1(a),(d)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherSalesRevenueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RevenueRecognitionAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents money paid in advance to protect the provider of a product or service, such as a lessor, against damage or nonpayment by the buyer or tenant (lessee) during the term of the agreement. Such damages may include physical damage to the property, theft of property, and other contractual breaches. Security deposits held may be interest or noninterest bearing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.15(a)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_SecurityDepositLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the number of debt instruments held. + References No definition available. + Details
Name: | wlfc_DebtInstrumentNumber
Namespace Prefix: | wlfc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of business days after the due date within which failure to pay interest would accelerate the Notes. + References No definition available. + Details
Name: | wlfc_DebtInstrumentNumberOfBusinessDaysWithinWhichFailureToPayInterestWouldAccelerateNotes
Namespace Prefix: | wlfc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the minimum number of days for which lease rent and maintenance reserve payments are past due. + References No definition available. + Details
Name: | wlfc_LeaseRentAndMaintenanceReservePaymentsReceivablePastDuePeriodMinimum
Namespace Prefix: | wlfc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the amount of maintenance reserve payments receivable that are more than 30 days past due. + References No definition available. + Details
Name: | wlfc_MaintenanceReservePaymentsReceivableOverThirtyDaysPastDue
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition A liability for future maintenance events that have a refundable aspect contingent on return conditions. + References No definition available. + Details
Name: | wlfc_MaintenanceReserves
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of Engines + References No definition available. + Details
Name: | wlfc_NumberOfEngines
Namespace Prefix: | wlfc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the amount of lease rent receivables that are more than 30 days past due. + References No definition available. + Details
Name: | wlfc_OperatingLeasesLeaseRentReceivableOverThirtyDaysPastDue
Namespace Prefix: | wlfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Organization [Line Items] + References No definition available. + Details
Name: | wlfc_OrganizationsLineItems
Namespace Prefix: | wlfc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=wlfc_SecuredCreditFacilityDueJune2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=wlfc_Series20171NotesPayableDueAugust2042Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=wlfc_SeriesB20171NotesPayableDueAugust2042Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=wlfc_WillisEngineStructuredTrustIiiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=wlfc_WOLFA340LLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |