Condensed Consolidated Statements of Cash Flows (Parenthetical) $ in Millions	6 Months Ended
Jun. 30, 2025 USD ($)
Statement of Cash Flows [Abstract]
Non-cash additions to equipment held for operating leases for associated total gain	$ 4.6

Non-Cash Additions To Equipment Held For Operating Leases For Associated Total Gain

No definition available.

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