SUPPLIER FINANCE PROGRAM (Details) - USD ($) $ in Thousands	Jun. 27, 2026	Dec. 27, 2025
SUPPLIER FINANCE PROGRAM
Outstanding payment obligations	$ 38,828	$ 56,324

Amount of outstanding confirmed supplier finance obligation.

No definition available.

Name:	vmi_SupplierFinanceProgramConfirmedObligationsOutstanding
Namespace Prefix:	vmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant