Note 4 - Stockholders' Equity (Details Textual) (USD $)
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1 Months Ended |
12 Months Ended |
0 Months Ended |
1 Months Ended |
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Apr. 21, 2013
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Apr. 21, 2009
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Dec. 17, 2014
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Dec. 31, 2014
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Dec. 31, 2013
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May 04, 2007
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Oct. 19, 2007
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Nov. 04, 2014
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Aug. 13, 2012
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Equity [Abstract] |
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Preferred Stock, Shares Authorized |
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5,000,000us-gaap_PreferredStockSharesAuthorized
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5,000,000us-gaap_PreferredStockSharesAuthorized
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Preferred Stock, Par or Stated Value Per Share |
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$ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
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$ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
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Common Stock, Shares Authorized |
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50,000,000us-gaap_CommonStockSharesAuthorized
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50,000,000us-gaap_CommonStockSharesAuthorized
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Common Stock, Par or Stated Value Per Share |
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$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
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$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
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Class of Warrant or Right, Number of Securities Called by Warrants or Rights |
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88,097us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
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3,141,499us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
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Term Of Warrant |
5 years
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1 year
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7 years
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Class of Warrant or Right, Exercise Price of Warrants or Rights |
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$ 3.5082us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
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3.52us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
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Proceeds from Warrant Exercises |
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$ 4,948,000us-gaap_ProceedsFromWarrantExercises
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Stock Repurchase Program, Number of Shares Authorized to be Repurchased |
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100,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
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Stock Repurchase Program, Authorized Amount |
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5,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1
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Treasury Stock, Value, Acquired, Cost Method |
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4,500,000us-gaap_TreasuryStockValueAcquiredCostMethod
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4,661,000us-gaap_TreasuryStockValueAcquiredCostMethod
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52,000us-gaap_TreasuryStockValueAcquiredCostMethod
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Treasury Stock, Value, Acquired, Cost Method, Excluding Related Party |
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3,000,000nhtc_TreasuryStockValueAcquiredCostMethodExcludingRelatedParty
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Treasury Stock, Shares, Acquired |
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359,840us-gaap_TreasuryStockSharesAcquired
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George K. Broady [Member] |
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Equity [Abstract] |
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Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |
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5.00%us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners / us-gaap_TitleOfIndividualAxis = nhtc_GeorgeKBroadyMember
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Treasury Stock, Value, Acquired, Cost Method |
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1,500,000us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_TitleOfIndividualAxis = nhtc_GeorgeKBroadyMember
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Series A Preferred Stock [Member] |
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Equity [Abstract] |
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Preferred Stock, Shares Outstanding |
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1,761,900us-gaap_PreferredStockSharesOutstanding / us-gaap_StatementClassOfStockAxis = us-gaap_SeriesAPreferredStockMember
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Preferred Stock, Dividends Per Share, Declared |
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$ 0.119us-gaap_PreferredStockDividendsPerShareDeclared / us-gaap_StatementClassOfStockAxis = us-gaap_SeriesAPreferredStockMember
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Share Price |
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$ 1.70us-gaap_SharePrice / us-gaap_StatementClassOfStockAxis = us-gaap_SeriesAPreferredStockMember
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Preferred Stock, Voting Rights |
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0.729
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Minimum [Member] | Series A Preferred Stock [Member] |
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Equity [Abstract] |
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Share Price |
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$ 10us-gaap_SharePrice / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_StatementClassOfStockAxis = us-gaap_SeriesAPreferredStockMember
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Initially Be Equal To [Member] | Series A Preferred Stock [Member] |
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Equity [Abstract] |
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Share Price |
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$ 1.70us-gaap_SharePrice / us-gaap_RangeAxis = nhtc_InitiallyBeEqualToMember / us-gaap_StatementClassOfStockAxis = us-gaap_SeriesAPreferredStockMember
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Five Year Warrants [Member] |
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Equity [Abstract] |
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Class of Warrant or Right, Number of Securities Called by Warrants or Rights |
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149,595us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = nhtc_FiveYearWarrantsMember
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Term Of Warrant |
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5 years
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One Year Warrants [Member] |
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Equity [Abstract] |
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Class of Warrant or Right, Number of Securities Called by Warrants or Rights |
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1,495,952us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = nhtc_OneYearWarrantsMember
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Term Of Warrant |
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1 year
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Seven Year Warrants [Member] |
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Equity [Abstract] |
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Class of Warrant or Right, Number of Securities Called by Warrants or Rights |
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1,407,855us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = nhtc_SevenYearWarrantsMember
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1,495,952us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = nhtc_SevenYearWarrantsMember
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Term Of Warrant |
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7 years
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Proceeds from Warrant Exercises |
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$ 4,900,000us-gaap_ProceedsFromWarrantExercises / us-gaap_ClassOfWarrantOrRightAxis = nhtc_SevenYearWarrantsMember
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Seven Year Warrants [Member] | Maximum [Member] |
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Equity [Abstract] |
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Class of Warrant or Right, Exercise Price of Warrants or Rights |
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$ 3.52us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = nhtc_SevenYearWarrantsMember / us-gaap_RangeAxis = us-gaap_MaximumMember
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Seven Year Warrants [Member] | Minimum [Member] |
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Equity [Abstract] |
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Class of Warrant or Right, Exercise Price of Warrants or Rights |
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$ 3.5108us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = nhtc_SevenYearWarrantsMember / us-gaap_RangeAxis = us-gaap_MinimumMember
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