Annual report pursuant to Section 13 and 15(d)

Equity-Based Compensation (Narrative) (Details)

v2.4.1.9
Equity-Based Compensation (Narrative) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
12 Months Ended
Jan. 03, 2015
Dec. 28, 2013
Dec. 29, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Equity-based compensation expense $ 9,805us-gaap_AllocatedShareBasedCompensationExpense $ 7,624us-gaap_AllocatedShareBasedCompensationExpense $ 10,210us-gaap_AllocatedShareBasedCompensationExpense
Equity-based compensation related tax benefit 3,308us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 2,575us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 3,554us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Total shares authorized under the plan 10,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized    
Total awards granted 6,790us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod    
Awards canceled 1,143us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherShareIncreaseDecrease    
Weighted-average grant date fair value $ 18.91us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue $ 17.59us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue $ 15.35us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Total intrinsic value of stock options and stock-settled stock appreciation rights exercised 51,795us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue 32,837us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue 20,590us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Total fair value of equity awards vested $ 7,568us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue $ 8,096us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue $ 10,211us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Stock Appreciation Rights (SARs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total awards granted 6,668us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
   
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total awards granted 8us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Deferred Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total awards granted 114us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Officers Upon Hire Or Promotion [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 20.00%usna_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage
/ us-gaap_TitleOfIndividualAxis
= usna_OfficersUponHireOrPromotionMember
   
Expiration from grant date 5 years 6 months    
Officers [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 50.00%usna_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage
/ us-gaap_TitleOfIndividualAxis
= us-gaap_OfficerMember
   
Directors [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 25.00%usna_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember