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PREFERRED STOCK (Details) (USD $)
0 Months Ended 12 Months Ended
Mar. 18, 2013
Dec. 31, 2014
Dec. 31, 2013
Mar. 31, 2013
Equity Payable [Abstract]        
Proceeds from Issuance of Convertible Preferred Stock   $ 1,010,000us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock $ 0us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock  
Preferred stock converted 2,690,056ztho_PreferredStockConversion 0ztho_PreferredStockConversion 2,690,056ztho_PreferredStockConversion  
Series II [Member]        
Equity Payable [Abstract]        
Preferred stock, shares outstanding (in shares)       0us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
Investors [Member]        
Equity Payable [Abstract]        
Proceeds from Issuance of Convertible Preferred Stock   1,010,000us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
   
Percentage of Convertible Preferred Stock of one share (in hundredths)   12.50%us-gaap_PreferredStockDividendRatePercentage
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
   
Shares of company's common stock per one warrant (in shares)   8.56us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
   
Share price (in dollars per share)   $ 4.00us-gaap_SharePrice
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
   
Number of unit sold (in shares)   260,000us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
   
Brightline Ventures I, LLC [Member] | Series II [Member]        
Equity Payable [Abstract]        
Value of convertible preferred stock converted into common stock 3,326,697ztho_ValueOfConvertiblePreferredStockConvertedIntoCommonStock
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineVenturesILlcMember
     
Value of accrued dividends on convertible preferred stock converted into common stock $ 533,000ztho_ValueOfAccruedDividendsOnConvertiblePreferredStockConvertedIntoCommonStock
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineVenturesILlcMember
     
Common stock issued for conversion of equity securities (in shares) 3,859,697us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineVenturesILlcMember