Annual report pursuant to Section 13 and 15(d)

EMPLOYEE BENEFIT PLANS (Details)

v2.4.1.9
EMPLOYEE BENEFIT PLANS (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
401(k) plans      
Employer's matching contribution (as a percent) 60.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent    
Maximum contribution by employer as a percentage of employee's compensation 5.00%us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent    
Employer's matching contribution before change (as a percent) 50.00%natr_DefinedContributionPlanEmployerMatchingContributionPercentBeforeChange    
Vesting period of employer's contributions 3 years    
Contributions by employer $ 838us-gaap_DefinedContributionPlanCostRecognized $ 832us-gaap_DefinedContributionPlanCostRecognized $ 551us-gaap_DefinedContributionPlanCostRecognized
Nonqualified deferred compensation plan      
Maximum percentage of annual salary and bonus that may be deferred 100.00%natr_DeferredCompensationArrangementsMaximumPercentageOfSalaryAndBonusThatMayBeDeferred    
Period for payment of obligation upon separation, one 3 years    
Period for payment of obligation upon separation, two 5 years    
Deferred compensation plan assets $ 1,038us-gaap_DeferredCompensationPlanAssets $ 971us-gaap_DeferredCompensationPlanAssets