LEASES - Rent Expense (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 29, 2023	Dec. 30, 2022	Dec. 31, 2021
LEASES
Rent expenses	$ 6.8	$ 6.5	$ 6.8

Amount of operating lease expense. Excludes sublease income.

No definition available.

Name:	wldn_OperatingLeaseRentExpenses
Namespace Prefix:	wldn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration