Quarterly report pursuant to Section 13 or 15(d)

Note Payable - Additional Information (Detail)

v2.4.1.9
Note Payable - Additional Information (Detail) (USD $)
3 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Sep. 30, 2014
Apr. 19, 2013
Note Payable [Line Items]          
Notes Payable, Total $ 944,707us-gaap_NotesPayable        
Adjustments to Additional Paid in Capital, Warrant Issued 55,293us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued        
Class of Warrant or Right, Exercise Price of Warrants or Rights         $ 0.75us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Interest Expense, Debt 2,764us-gaap_InterestExpenseDebt 2,764us-gaap_InterestExpenseDebt      
Debt instrument, unamortized discount 958,530us-gaap_DebtInstrumentUnamortizedDiscount     955,766us-gaap_DebtInstrumentUnamortizedDiscount  
Warrant          
Note Payable [Line Items]          
Fair Value Assumptions, Risk Free Interest Rate 2.64%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_WarrantMember
       
Fair Value Assumptions, Expected Dividend Rate 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_WarrantMember
       
Fair Value Assumptions, Expected Term 10 years        
Fair Value Assumptions, Expected Volatility Rate 114.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_WarrantMember
       
Massachusetts Life Sciences Center          
Note Payable [Line Items]          
Subordinated Debt     $ 1,000,000us-gaap_SubordinatedDebt
/ dei_LegalEntityAxis
= arth_MassachusettsLifeSciencesCenterMember
   
Debt Instrument, Payment Terms     The loan bears interest at a rate of 10% per annum, and will become fully due and payable on the earlier of (i) September 30, 2018, (ii) the occurrence of an event of default under the MLSC Loan Agreement, or (iii) the completion of a sale of substantially all of our assets, a change-of-control transaction or one or more financing transactions in which we receive net proceeds of $5,000,000 or more in a 12-month period.    
Warrants Issued To Purchase Of Common Stock     145,985arth_WarrantsIssuedToPurchaseOfCommonStock
/ dei_LegalEntityAxis
= arth_MassachusettsLifeSciencesCenterMember
   
Class Of Warrant Or Right Expiration Date     Sep. 30, 2023    
Class of Warrant or Right, Exercise Price of Warrants or Rights     $ 0.27us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ dei_LegalEntityAxis
= arth_MassachusettsLifeSciencesCenterMember