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Revenue derived from maintenance services provided under contracts or arrangements with clients. For example, it may include the maintenance of software, plant and equipment, and facilities.

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The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39896-112707

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Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Section S99
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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.

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Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

No definition available.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
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-Section S99
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Represents the amount of notes receivable from the related party, prepaid at discount.

No definition available.

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Represents the number of aircraft sold by the entity.

No definition available.

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Represents the number of engines sold by the entity.

No definition available.

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Represents the amounts owed to the entity related to the minimum guarantee, which is deducted from payment made in cash under transactions with related party.

No definition available.

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Represents the amount of aggregate net book value of engines and aircraft sold.

No definition available.

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Represents the amount of gain (loss) on sale of engines and aircraft.

No definition available.

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Represents the percentage of discount at which note is prepaid in cash.

No definition available.

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Represents the amount of cash inflow from sale of engines and aircraft.

No definition available.

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Represents the sale of consigned parts of teardown engines under the agreement with related party.

No definition available.

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Represents the cash payment made by the entity in the significant acquisition or disposal.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Represents the cash payment made by the entity to the creditors in the significant acquisition or disposal.

No definition available.

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Represents the cash payment made by the entity to the shareholders of related party in the significant acquisition or disposal.

No definition available.

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Represents the cash received by the entity in the significant acquisition or disposal.

No definition available.

Name:	wlfc_SignificantAcquisitionsAndDisposalsAcquisitionCashReceived
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
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Namespace Prefix:
Data Type:	na
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