Note B - Fair Value Measures (Details Textual) - USD ($) $ in Thousands	Sep. 26, 2020	Dec. 28, 2019
Nonfinancial Assets, Fair Value Disclosure	$ 0	$ 0

The amount of nonfinancial assets measured at fair value.

No definition available.

Name:	usna_NonfinancialAssetsFairValueDisclosure
Namespace Prefix:	usna_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant