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COMMON STOCK (Details) (USD $)
0 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended 3 Months Ended 0 Months Ended
Nov. 18, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Mar. 18, 2015
Feb. 24, 2015
Director
Dec. 03, 2013
Oct. 28, 2013
Mar. 01, 2015
Aug. 20, 2013
Sep. 30, 2013
Jan. 02, 2014
Director
Jan. 22, 2013
Director
Sep. 18, 2013
Feb. 28, 2013
Feb. 12, 2013
Jan. 08, 2015
Subsidiary, Sale of Stock [Line Items]                                    
Warrants exercised for cash (in shares)   1,756,088ztho_WarrantsExercised                                
Cashless exercise of warrants (in shares)   1,756,088ztho_StockIssuedDuringPeriodSharesCashlessWarrants 0ztho_StockIssuedDuringPeriodSharesCashlessWarrants                              
Warrant exercise price (in dollars per share)   $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1                         $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 $ 1.25us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1    
Warrants exercised for cash   $ 2,195,110ztho_StockIssuedDuringPeriodValueWarrantsExercised $ 0ztho_StockIssuedDuringPeriodValueWarrantsExercised $ 2,489,846ztho_StockIssuedDuringPeriodValueWarrantsExercised                            
Expense for modification of warrants previously issued for services   4,789,801ztho_ExpenseForModificationOfWarrantsPreviouslyIssuedForServices 0ztho_ExpenseForModificationOfWarrantsPreviouslyIssuedForServices 5,780,457ztho_ExpenseForModificationOfWarrantsPreviouslyIssuedForServices                            
Exercised cashless stock options (in shares)     0ztho_ExercisedCashlessStockOptionsShares 100,528ztho_ExercisedCashlessStockOptionsShares                            
Warrants issued to purchase common stock (in shares)                             234,286us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights      
Exercised stock options for cash     0us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised 77,734us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised                            
Cashless stock options exercised (in shares)       202,250ztho_CashlessExerciseOfOptionsShares                            
Proceeds from Issuance Initial Public Offering 1,210,165us-gaap_ProceedsFromIssuanceInitialPublicOffering                                  
Number of shares issued under settlement agreement (in shares)                                 875,000ztho_NumberOfSharesIssuedUnderSettlementAgreement  
Stock to be issued for settlement loss         1,881,250ztho_AdjustmentsToAdditionalPaidInCapitalStockToBeIssuedForSettlementLoss                          
Subsequent Event [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Warrant exercise price (in dollars per share)           $ 0.64us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
                      $ 0.64us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Proceeds from issuance of private placement           75,000us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
                       
Common Stock [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Cashless exercise of warrants (in shares)     0ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
3,606,157ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                           
Company stock price on date of modification (in dollars per share)   $ 2.30ztho_CompanyStockPriceOnDateOfModification
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                               
Volatility of stock price (in hundredths)   109.96%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                               
Discount rate used (in hundredths)   0.06%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                               
Exercised cashless stock options (in shares)     0ztho_ExercisedCashlessStockOptionsShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
100,528ztho_ExercisedCashlessStockOptionsShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                           
Shares sold (in shares) 1,866,667us-gaap_StockIssuedDuringPeriodSharesIssuedForCash
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                                 
Share price (in dollars per share) $ 0.75us-gaap_SharePrice
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
                                 
Common Stock [Member] | Subsequent Event [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Number of non executive directors             4ztho_NumberOfNonExecutiveDirectors
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
                     
Warrant exercise price (in dollars per share)                                   $ 0.35us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Warrants issued to purchase common stock (in shares)                                   54,400,204us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Restricted Shares of Common Stock [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Shares issued for services (in shares)               550,000us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockMember
220,000us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockMember
                 
Consulting agreement termination date               Jan. 31, 2015 Jan. 31, 2014                  
Common stock valued               569,800ztho_CommonStockValued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockMember
                   
Restricted Shares of Common Stock [Member] | Subsequent Event [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Consulting agreement termination date                   Mar. 01, 2016                
Warrant [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Cashless exercise of warrants (in shares)                       7,172,751ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Warrant exercise price (in dollars per share) $ 1.00us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
                  $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
$ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Warrant exercise description                     for every ten $1.50 warrants exercised, the holder received 4.5 shares of Common Stock (fractional shares were rounded up)              
Exercise price of unexercised warrants (in dollars per share)                     $ 1.25ztho_WarrantsExercisePriceAfterReduction
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Base number of warrants consider for conversion of shares (in shares)                     10ztho_BaseNumberOfWarrantsConsideredForConversionOfShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Number of shares to be issued for exercise of ten warrants (in shares)                     4.5ztho_NumberOfSharesToBeIssuedForExerciseOfTenWarrants
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Exercised cashless stock options (in shares)                       3,227,742ztho_ExercisedCashlessStockOptionsShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Warrants converted into common stock                       5,718,750ztho_WarrantsConvertedIntoCommonStock
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Common stock issued for conversion of warrants (in shares)                       2,573,438ztho_CommonStockIssuedForConversionOfWarrantsInShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Loss on equity modification                       (990,656)ztho_GainLossOnModificationOfEquity
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
           
Unexercised warrants description                     for every five warrants owned, each remaining holder of $1.50 warrants received one additional warrant with an exercise price of $1.25 per share.              
Base number of warrants considered for additional warrant (in shares)                     5ztho_BaseNumberOfWarrantsConsideredForAdditionalWarrant
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Number of warrants that not exercised (in shares)                     11,880,047ztho_NumberOfWarrantsThatNotExercised
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Warrants issued to purchase common stock (in shares) 1,400,000us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
                  2,376,009us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Warrants issued (in shares)                     2,316,597ztho_DebtInstrumentConvertibleNumberOfWarrantsIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Settlement to additional paid in capital for related derivative liability                     1,712,356ztho_SettlementToAdditionalPaidInCapitalForRelatedDerivativeLiability
/ us-gaap_StatementClassOfStockAxis
= us-gaap_WarrantMember
             
Common Stock Payable [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Number of shares issued under settlement agreement (in shares)                                 875,000ztho_NumberOfSharesIssuedUnderSettlementAgreement
/ us-gaap_StatementClassOfStockAxis
= ztho_CommonStockPayableMember
 
Stock to be issued for settlement loss         1,881,250ztho_AdjustmentsToAdditionalPaidInCapitalStockToBeIssuedForSettlementLoss
/ us-gaap_StatementClassOfStockAxis
= ztho_CommonStockPayableMember
                         
Investors [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Warrants exercised for cash (in shares)       369,759ztho_WarrantsExercised
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
                           
Cashless exercise of warrants (in shares)       909,784ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
                           
Warrants exercised for cash       210,880ztho_StockIssuedDuringPeriodValueWarrantsExercised
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
                           
Exercised cashless stock options (in shares)       378,415ztho_ExercisedCashlessStockOptionsShares
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
                           
Share price (in dollars per share)     $ 4.00us-gaap_SharePrice
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_InvestorMember
                             
Non-Executive Directors [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Shares issued for services (in shares)                         285,716us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
114,944us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
       
Number of non executive directors                     3ztho_NumberOfNonExecutiveDirectors
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
  4ztho_NumberOfNonExecutiveDirectors
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
4ztho_NumberOfNonExecutiveDirectors
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
       
Shares issued for services (in shares)                         71,429ztho_SharesIssuedForServices
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
28,736ztho_SharesIssuedForServices
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
       
Share-based compensation expense                         160,001us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
200,002us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_NonExecutiveDirectorMember
       
Former Employee [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Number of former employees exercised stock options       2ztho_NumberOfFormerEmployeesExercisedStockOptions
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_FormerEmployeeMember
                           
Exercised stock options for cash (in shares)       91,400us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= ztho_FormerEmployeeMember
                           
Brightline [Member] | Common Stock [Member]                                    
Subsidiary, Sale of Stock [Line Items]                                    
Shares sold (in shares)                     376,000us-gaap_StockIssuedDuringPeriodSharesIssuedForCash
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember
      468,571us-gaap_StockIssuedDuringPeriodSharesIssuedForCash
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember
     
Share price (in dollars per share)                     $ 1.25us-gaap_SharePrice
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember
      $ 1.05us-gaap_SharePrice
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember
     
Proceeds from issuance of private placement                     $ 470,000us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember
      $ 492,000us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= ztho_BrightlineMember