Annual report pursuant to Section 13 and 15(d)

Intangible Assets (Schedule Of Finite And Indefinite Lived Intangible Assets) (Details)

v2.4.1.9
Intangible Assets (Schedule Of Finite And Indefinite Lived Intangible Assets) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Jan. 03, 2015
Dec. 28, 2013
Schedule Of Finite and Indefinite Intangible Assets [Line Items]    
Amortized intangible assets, Net carrying amount $ 2,376us-gaap_FiniteLivedIntangibleAssetsNet  
Unamortized intangible assets 38,576us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill 39,462us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Total, Gross carrying amount 42,850us-gaap_IntangibleAssetsGrossExcludingGoodwill 43,834us-gaap_IntangibleAssetsGrossExcludingGoodwill
Total, Net carrying amount 40,952us-gaap_IntangibleAssetsNetExcludingGoodwill 42,329us-gaap_IntangibleAssetsNetExcludingGoodwill
Trade Name And Trademarks [Member]    
Schedule Of Finite and Indefinite Intangible Assets [Line Items]    
Amortized intangible assets, Gross carrying amount 4,274us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
4,372us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
Accumulated amortization (1,898)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
(1,505)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
Amortized intangible assets, Net carrying amount 2,376us-gaap_FiniteLivedIntangibleAssetsNet
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
2,867us-gaap_FiniteLivedIntangibleAssetsNet
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= usna_TradeNameAndTrademarksMember
Weighted-average amortization period (years) 10 years 10 years
Product Formulas [Member]    
Schedule Of Finite and Indefinite Intangible Assets [Line Items]    
Unamortized intangible assets 9,425us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeSecretsMember
9,641us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeSecretsMember
Direct Sales License [Member]    
Schedule Of Finite and Indefinite Intangible Assets [Line Items]    
Unamortized intangible assets $ 29,151us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_LicensingAgreementsMember
$ 29,821us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_LicensingAgreementsMember