Quarterly report pursuant to Section 13 or 15(d)

Capital Transactions (Details 3)

v2.4.1.9
Capital Transactions (Details 3) (USD $)
In Thousands, except Share data, unless otherwise specified
0 Months Ended 3 Months Ended 0 Months Ended
Sep. 19, 2013
Aug. 29, 2013
Mar. 31, 2015
Mar. 31, 2014
Sep. 19, 2014
Dec. 31, 2014
Stock options            
Share Based Compensation            
Outstanding options to purchase (in shares)     2,071,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    2,037,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Exercisable (in shares)     1,119,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    1,069,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Expected to vest (in shares)     780,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    794,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Aggregate Intrinsic value, outstanding     $ 2,638us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    $ 6,801us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Aggregate Intrinsic value, exercisable     2,167us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    4,928us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Aggregate Intrinsic value, expected to vest     448us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    1,779us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Share-based compensation, additional disclosures            
Special one-time cash dividend paid per common share (in dollars per share) $ 1.50natr_SpecialOneTimeCommonStockDividendsPerShareCashPaid
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 1.50natr_SpecialOneTimeCommonStockDividendsPerShareCashPaid
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Weighted-average assumptions used to calculate fair value of options granted            
Risk-free interest rate (as a percent)     1.50%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Dividend yield (as a percent)     2.80%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Stock options | Minimum            
Weighted-average assumptions used to calculate fair value of options granted            
Expected life     5 years      
Expected volatility (as a percent)     46.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
     
Stock options | Maximum            
Weighted-average assumptions used to calculate fair value of options granted            
Expected life     6 years      
Expected volatility (as a percent)     52.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
     
RSUs            
Share-based compensation, additional disclosures            
Share-based compensation expense     756us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
197us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Related tax benefits     299us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
78us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
   
Unrecognized share-based compensation expense     3,942us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
    849us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
Weighted-average period over which the remaining compensation expense is expected to be recognized     2 years 2 months 12 days      
Minimum statutory withholding requirement paid on behalf of employees (in shares)     8natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsMinimumWithholdingRequirements
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
     
Performance-based RSUs            
Share-based compensation, additional disclosures            
Vesting period based on achieving operating income and earnings per share targets     1 year      
Performance-based RSUs | Maximum            
Share-based compensation, additional disclosures            
Potential compensation expense     3,600natr_ShareBasedCompensationPotentialCompensationExpenseToBeRecognized
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedRestrictedStockUnitsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
     
SARs            
Share-based compensation, additional disclosures            
Special one-time cash dividend paid per common share (in dollars per share)   $ 1.50natr_SpecialOneTimeCommonStockDividendsPerShareCashPaid
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
    $ 1.50natr_SpecialOneTimeCommonStockDividendsPerShareCashPaid
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
 
2012 Stock Incentive Plan | RSUs            
Number of Shares            
Units outstanding at the beginning of the period (in shares)     180,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Granted (in shares)     569,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Issued (in shares)     (30,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Forfeited or canceled (in shares)     (5,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Units outstanding at the end of the period (in shares)     714,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Weighted Average Grant Date Fair Value            
Units outstanding at the beginning of the period (in dollars per share)     $ 15.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Granted (in dollars per share)     $ 12.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Issued (in dollars per share)     $ 13.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Forfeited or canceled (in dollars per share)     $ 12.93us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Units outstanding at the end of the period (in dollars per share)     $ 12.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Share-based compensation, additional disclosures            
Vesting period     3 years      
Discount for lack of marketability ( as a percent)     17.50%us-gaap_FairValueInputsDiscountForLackOfMarketability
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
2012 Stock Incentive Plan | RSUs | Minimum            
Share-based compensation, additional disclosures            
Vesting period     12 months      
2012 Stock Incentive Plan | RSUs | Maximum            
Share-based compensation, additional disclosures            
Vesting period     48 months      
2012 Stock Incentive Plan | RSUs | Board of Directors            
Number of Shares            
Number of shares subject to restriction period     32,000natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedSubjectToRestrictionPeriodNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
    32,000natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedSubjectToRestrictionPeriodNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
Restriction period     2 years      
2012 Stock Incentive Plan | Performance-based RSUs            
Weighted-average assumptions used to calculate fair value of options granted            
Weighted-average grant date fair value (in dollars per share)     $ 12.13us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedRestrictedStockUnitsMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
2012 Stock Incentive Plan | Time-based RSUs            
Weighted-average assumptions used to calculate fair value of options granted            
Weighted-average grant date fair value (in dollars per share)     $ 13.49us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= natr_TimeBasedRestrictedStockUnitsMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
2012 Stock Incentive Plan | SARs            
Number of Shares            
Units outstanding at the beginning of the period (in shares)     30,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Forfeited or canceled (in shares)     (10,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Units outstanding at the end of the period (in shares)     20,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Weighted Average Grant Date Fair Value            
Units outstanding at the beginning of the period (in dollars per share)     $ 5.47us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Forfeited or canceled (in dollars per share)     $ 5.86us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Units outstanding at the end of the period (in dollars per share)     $ 5.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Share-based compensation, additional disclosures            
Number of shares of common stock used for determining the fair value, or strike price, of grants     1natr_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNumberOfSharesOfCommonStockForFairValueOfGrant
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Share-based compensation expense     3us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Related tax benefits     1us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
     
Unrecognized share-based compensation expense     $ 71us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
    $ 150us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
Weighted-average period over which the remaining compensation expense is expected to be recognized     2 years 2 months 12 days      
2012 Stock Incentive Plan | SARs | Minimum            
Share-based compensation, additional disclosures            
Vesting period     12 months      
2012 Stock Incentive Plan | SARs | Maximum            
Share-based compensation, additional disclosures            
Vesting period     48 months