Quarterly report pursuant to Section 13 or 15(d)

Capital Transactions (Details 2)

v2.4.1.9
Capital Transactions (Details 2) (USD $)
In Thousands, except Per Share data, unless otherwise specified
0 Months Ended 3 Months Ended
Sep. 19, 2013
Aug. 29, 2013
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Stock options          
Number of shares          
Options outstanding at the beginning of the period (in shares)     2,037us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Granted (in shares)     310us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Forfeited or canceled (in shares)     (49)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Exercised (in shares)     (227)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Options outstanding at the end of the period (in shares)     2,071us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Weighted Average Exercise Price Per Share          
Options outstanding at the beginning of the period (in dollars per share)     $ 11.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Granted (in dollars per share)     $ 14.27us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Forfeited or canceled (in dollars per share)     $ 15.75us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Exercised (in dollars per share)     $ 7.63us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Options outstanding at the end of the period (in dollars per share)     $ 12.43us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ 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
   
Time-based stock options          
Share-based compensation, related information          
Share-based compensation expense     $ 580us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
$ 897us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
 
Related tax benefit     229us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
354us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
 
Unrecognized share-based compensation expense     2,589us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
  2,018us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
Weighted-average period over which the remaining compensation cost is expected to be recognized     1 year 10 months 24 days    
Time-based stock options | Maximum          
Share-based compensation, additional disclosures          
Vesting period     48 months    
Performance based stock options operating income margins          
Share-based compensation, additional disclosures          
Operating income margin, one (as a percent)     6.00%natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOperatingMarginsOne
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedStockOptionsVestingUponAchievingOperatingIncomeMarginsMember
   
Operating income margin, two (as a percent)     8.00%natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOperatingMarginsTwo
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedStockOptionsVestingUponAchievingOperatingIncomeMarginsMember
   
Operating income margin, three (as a percent)     10.00%natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOperatingMarginsThree
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedStockOptionsVestingUponAchievingOperatingIncomeMarginsMember
   
Period of time during which operating income margins must be achieved in order to vest in performance based stock options     12 months    
Consecutive period of time used to assess operating income margins which determine vesting     15 months    
Performance based stock options sales and operating income margins          
Share-based compensation, additional disclosures          
Vesting period     2 years    
Performance based stock options sales and operating income margins | Minimum          
Share-based compensation, additional disclosures          
Operating income margin, two (as a percent)     8.00%natr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOperatingMarginsTwo
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedStockOptionsVestingUponAchievingSalesAndOperatingIncomeMarginsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
   
Performance based stock options sales          
Share-based compensation, additional disclosures          
Vesting period based on achieving annual net sales targets     1 year    
Performance based stock options sales | Maximum          
Share-based compensation, related information          
Potential compensation expense     $ 800natr_ShareBasedCompensationPotentialCompensationExpenseToBeRecognized
/ us-gaap_AwardTypeAxis
= natr_PerformanceBasedStockOptionsVestingUponAchievingSalesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
   
2012 Stock Incentive Plan          
Share Based Compensation          
Number of shares authorized under the plan         1,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
Additional number of shares authorized under the plan     1,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
   
2012 Stock Incentive Plan | Time-based stock options          
Number of shares          
Granted (in shares)     310us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
   
Weighted Average Exercise Price Per Share          
Granted (in dollars per share)     $ 14.27us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
   
Share-based compensation, additional disclosures          
Expiration period     10 years    
Weighted-average assumptions used to calculate fair value of options granted          
Weighted-average grant date fair value (in dollars per share)     $ 4.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= natr_TimeBasedStockOptionsMember
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2012Member
   
2009 Incentive Plan | Maximum          
Share Based Compensation          
Number of shares authorized under the plan     400us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= natr_IncentivePlan2009Member
/ us-gaap_RangeAxis
= us-gaap_MaximumMember