This element represents the aggregate cost of investments accounted for under the equity method of accounting.

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 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 12

-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ 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 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

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Balance Type:	credit
Period Type:	duration

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the initial carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of engines in lease portfolio of equity method investee.

+ References

No definition available.

+ Details

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Namespace Prefix:	wlfc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of engines purchased by the entity for transfer to the lease portfolio of equity method investee.

+ References

No definition available.

+ Details

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Namespace Prefix:	wlfc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of engines transferred to equity method investee to form part of initial lease portfolio.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Details

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Investments (Details) (USD $)	3 Months Ended	1 Months Ended	46 Months Ended	1 Months Ended
Investments (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2011 engine	Mar. 31, 2015 engine	Oct. 31, 2014	Dec. 31, 2014	May 25, 2011	Jun. 03, 2014
Investments
Investment in joint venture	$ 42,574,000us-gaap_EquityMethodInvestments		$ 42,574,000us-gaap_EquityMethodInvestments		$ 41,590,000us-gaap_EquityMethodInvestments
Capital contribution to joint ventures	(630,000)
WMES
Investments
Ownership interest (as a percent)	50.00%		50.00%
Initial capital contribution						8,000,000
Number of engines transferred to the joint venture		7
Number of engines purchased			21
Capital contributions to date	20,400,000		20,400,000
Investment in joint venture	27,663,000		27,663,000		26,672,000
Number of engines in lease portfolio	28
Capital contribution to joint ventures	(630,000)
CASC
Investments
Ownership interest (as a percent)							50.00%
Investment in joint venture	14,911,000		14,911,000		14,918,000
Capital contribution to joint ventures				$ 15,000,000