SCHEDULE I - Parent Company Information (Details 4) (Parent Company, USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Parent Company
Equity in income of subsidiaries
Equity in income of subsidiaries, tax	$ 199	$ 3,357	$ 8,749

Represents the tax amount on earnings (losses) of affiliates and subsidiaries during the period.

No definition available.

Name:	wlfc_TaxOnEarningsLossesOfAffiliatesAndSubsidiaries
Namespace Prefix:	wlfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration