Annual report pursuant to Section 13 and 15(d)

Note 5 - Stock-Based Compensation (Details Textual)

v2.4.1.9
Note 5 - Stock-Based Compensation (Details Textual) (USD $)
12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 30, 2008
Aug. 13, 2012
Dec. 29, 2008
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]          
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense $ 0us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense $ 0us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 1,083us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant        
Allocated Share-based Compensation Expense 49,000us-gaap_AllocatedShareBasedCompensationExpense 110,000us-gaap_AllocatedShareBasedCompensationExpense      
Stock Repurchase Program, Number of Shares Authorized to be Repurchased       100,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased  
Share-Based Compensation Incentive Compensation Period   3 years      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized $ 31,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized        
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 1 year        
Maximum [Member]          
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant     2,050,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
   
2007 Plan [Member]          
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized     500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
/ us-gaap_PlanNameAxis
= nhtc_Year2007PlanMember
   
2007 Plan [Member] | Maximum [Member]          
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant         1,550,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= nhtc_Year2007PlanMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Restricted Stock [Member] | 2007 Plan [Member]          
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years