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STOCK OPTION PLAN AND WARRANTS (Details) (USD $)
3 Months Ended 12 Months Ended 0 Months Ended
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Aug. 20, 2013
Sep. 30, 2014
Sep. 18, 2013
Feb. 28, 2013
Nov. 18, 2013
Oct. 21, 2013
Class of Warrant or Right [Line Items]                  
Exercised cashless warrants (in shares) 1,756,088ztho_StockIssuedDuringPeriodSharesCashlessWarrants 0ztho_StockIssuedDuringPeriodSharesCashlessWarrants              
Stock options exercised (in shares)   0ztho_ExercisedStockOptionsForCashInShares 91,400ztho_ExercisedStockOptionsForCashInShares            
Exercised cashless stock options (in shares)   0ztho_ExercisedCashlessStockOptionsShares 100,528ztho_ExercisedCashlessStockOptionsShares            
Warrants [Roll Forward]                  
Outstanding at beginning of period (in shares)         55,334,490us-gaap_ClassOfWarrantOrRightOutstanding        
Exercised (in shares) (1,756,088)ztho_WarrantsExercised                
Outstanding, end of period (in shares)         55,334,490us-gaap_ClassOfWarrantOrRightOutstanding        
Warrants weighted average exercise price [Roll Forward]                  
Outstanding at beginning of period (in dollar per share)           $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 $ 1.25us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1    
Outstanding, end of period (in dollar per share) $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1         $ 1.50us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 $ 1.25us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1    
Warrants issued to purchase common stock (in shares)           234,286us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights      
Common Stock [Member]                  
Class of Warrant or Right [Line Items]                  
Exercised cashless warrants (in shares)   0ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
3,606,157ztho_StockIssuedDuringPeriodSharesCashlessWarrants
/ 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
           
Warrant [Member]                  
Warrants [Roll Forward]                  
Outstanding at beginning of period (in shares) 23,392,811us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
16,688,265us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
23,392,811us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Granted (in shares)   0ztho_WarrantsGranted
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
4,010,295ztho_WarrantsGranted
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Exercised (in shares)   0ztho_WarrantsExercised
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
(2,287,730)ztho_WarrantsExercised
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Cashless Exercises (in shares)   0ztho_WarrantsCashlessWarrantActivity
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
(8,082,535)ztho_WarrantsCashlessWarrantActivity
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Expired and Cancelled (in shares)   (241,914)ztho_WarrantsExpiredAndCancelled
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
(344,576)ztho_WarrantsExpiredAndCancelled
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Outstanding, end of period (in shares)   16,446,351us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
16,688,265us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Exercisable at end of period (in shares)   16,446,351ztho_WarrantsExersisable
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
16,688,265ztho_WarrantsExersisable
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Warrants weighted average exercise price [Roll Forward]                  
Outstanding at beginning of period (in dollar per share) $ 1.46us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.44us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.46us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Granted (in dollar per share)   0ztho_WarrantsGrantedWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.18ztho_WarrantsGrantedWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Exercised (in dollar per share)   0ztho_WarrantsExercisedWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.28ztho_WarrantsExercisedWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Cashless Exercises (in dollar per share)   0ztho_CashlessWarrantWeightedAveragePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.43ztho_CashlessWarrantWeightedAveragePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Expired and cancelled (in dollar per share)   0.87ztho_WarrantsExpiredAndCancelledWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
0.88ztho_WarrantsExpiredAndCancelledWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Outstanding, end of period (in dollar per share)   1.44us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.44us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Exercisable at end of period (in dollar per share)   1.44ztho_WarrantsExercisableWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
1.44ztho_WarrantsExercisableWeightedAverageExercisePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
           
Warrants issued to purchase common stock (in shares)       2,376,009us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
  234,286us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
  1,400,000us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
30,000us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
Warrants issued (in shares)       2,316,597ztho_DebtInstrumentConvertibleNumberOfWarrantsIssued
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
         
Warrant exercise price (in dollars per share)       $ 1.50ztho_WarrantExercisePriceOfSharesAuthorized
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
  $ 1.50ztho_WarrantExercisePriceOfSharesAuthorized
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
  $ 1.00ztho_WarrantExercisePriceOfSharesAuthorized
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
 
Exercise price of unexercised warrants (in dollars per share)       $ 1.25ztho_WarrantsExercisePriceAfterReduction
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
         
Base number of warrants considered for additional warrant (in shares)       5ztho_BaseNumberOfWarrantsConsideredForAdditionalWarrant
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
         
Warrant [Member] | Minimum [Member]                  
Warrants weighted average exercise price [Roll Forward]                  
Inception to date, weighted average issue price (in dollars per share)   0.71ztho_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsIssuesInceptionToDateWeightedAverageIssueDatePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
0.71ztho_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsIssuesInceptionToDateWeightedAverageIssueDatePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
           
Warrant [Member] | Maximum [Member]                  
Warrants weighted average exercise price [Roll Forward]                  
Inception to date, weighted average issue price (in dollars per share)   1.50ztho_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsIssuesInceptionToDateWeightedAverageIssueDatePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
1.50ztho_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsIssuesInceptionToDateWeightedAverageIssueDatePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= us-gaap_WarrantMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember