Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Nonrecurring impairment charges related to the write-off of production-related equipment and inventory. This tag is used when an Entity charges this cost to cost of goods sold.

+ 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 210.5-03.2(a))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

- Definition

Equipment held for sale.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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Namespace Prefix:	wlfc_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Details

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- Details

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Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Assets at fair value and gains (losses) recorded
Equipment held for sale	$ 25,971		$ 23,454
Total losses on assets	(2,036)	$ (24)
Asset write-down	2,036	$ 24
Unamortized debt issuance cost	$ 12,600
Level 1
Assets at fair value and gains (losses) recorded
Equipment held for sale
Nonrecurring
Assets at fair value and gains (losses) recorded
Equipment held for sale	$ 3,307
Nonrecurring \| Level 2
Assets at fair value and gains (losses) recorded
Equipment held for sale	$ 3,307