Name:	wlfc_ContractWithCustomerLiability
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

No definition available.

Name:	wlfc_ContractWithCustomerLiabilityRevenueExpectedToBeRecognized
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

No definition available.

Name:	wlfc_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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.

No definition available.

Name:	wlfc_DisaggregationOfRevenueLineItems
Namespace Prefix:	wlfc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of lease rent receivables that are more than 30 days past due.

No definition available.

Name:	wlfc_LeaseRentReceivablePastDue
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of maintenance receivables that are more than 30 days past due.

No definition available.

Name:	wlfc_MaintenanceReserveReceivablePastDue
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the number of performance obligations identified.

No definition available.