Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation - Additional Information (Detail)

v2.4.1.9
Stock Plans and Stock-Based Compensation - Additional Information (Detail) (USD $)
12 Months Ended 1 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2013
Jun. 30, 2014
Sep. 30, 2013
Jan. 01, 2015
Dec. 31, 2007
Jun. 03, 2014
Dec. 31, 2010
Apr. 30, 2014
Jan. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Number of shares, Outstanding 991,010us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber 577,253us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber 577,253us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber                
Allocated share-based compensation expense $ 1,284,000us-gaap_ShareBasedCompensation $ 875,000us-gaap_ShareBasedCompensation                  
Expected dividend yield 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate                  
Fair value of options vested 1,000,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 900,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1                  
Share based compensation, stock option, unamortized expense 1,900,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions 1,200,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions 1,200,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions                
Share based compensation, stock option, unamortized expense vesting period 3 years 3 years 10 months 24 days                  
Share reserved for issue 3,317,963us-gaap_CommonStockCapitalSharesReservedForFutureIssuance 2,320,021us-gaap_CommonStockCapitalSharesReservedForFutureIssuance 2,320,021us-gaap_CommonStockCapitalSharesReservedForFutureIssuance                
Conversion of incentive award from liability to equity accounting 121,000us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebt 16,945,000us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebt                  
Options to purchase common stock, unvested                 14,623us-gaap_ClassOfWarrantOrRightOutstanding    
Stock Plan Activity [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, expiration period     10 years                
Number of shares, Outstanding   60,847us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
60,847us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
               
Change in exercise price     $ 5us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingPeriodIncreaseDecreaseWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
               
Stock option, Incremental expense resulting from modification     200,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
               
Allocated share-based compensation expense     200,000us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
               
Scientific Advisors and Consultants [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, expiration period 10 years                    
Share based compensation arrangement by share based payment award, award vesting period 60 months                    
Allocated share-based compensation expense 8,000us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
17,000us-gaap_ShareBasedCompensation
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
                 
Options to purchase common stock 10,000us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
6,833us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
6,833us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
               
Options to purchase common stock, unvested 13,416us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
                   
Incentive award issued   2,335us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
                 
Incentive awards outstanding, Unvested   1,752us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
1,752us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_AwardTypeAxis
= cyma_ScientificAdvisorsAndConsultantsMember
               
2013 Equity Incentive Plan [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, expiration period         10 years            
Share based compensation arrangement percentage increase in share reserved         5.00%cyma_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInSharesReservedPercentage
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
           
Number of additional shares authorized       500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
             
Shares available for grant 311,300us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
                   
2013 Equity Incentive Plan [Member] | Subsequent Event [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Increased in shares available for issuance           734,805cyma_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantPeriodIncreaseDecrease
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
         
2013 Equity Incentive Plan [Member] | Incentive Stock Options For Employees And Directors [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, exercise price percentage         100.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
/ us-gaap_AwardTypeAxis
= cyma_IncentiveStockOptionsForEmployeesAndDirectorsMember
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
           
2013 Equity Incentive Plan [Member] | Nonqualified options to employees, directors, and consultants [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, exercise price percentage         85.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
/ us-gaap_AwardTypeAxis
= cyma_NonQualifiedStockOptionsMember
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
           
2013 Equity Incentive Plan [Member] | Restricted Stock [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, exercise price percentage         85.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
           
2013 Equity Incentive Plan [Member] | Restricted Stock [Member] | Minimum [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, award vesting period         4 years            
2013 Equity Incentive Plan [Member] | Restricted Stock [Member] | Maximum [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, award vesting period         5 years            
2013 Equity Incentive Plan [Member] | Stock options to 10% stockholders [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, exercise price percentage             110.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
/ us-gaap_AwardTypeAxis
= cyma_StockOptionsToTenPercentShareholdersMember
/ us-gaap_PlanNameAxis
= cyma_EquityIncentivePlanTwoThousandAndThirteenMember
       
Share based compensation arrangement by share based payment award, award vesting period             5 years        
Incentive Awards [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, expiration period   10 years                  
Share based compensation arrangement by share based payment award, award vesting period 4 years             2 years      
Allocated share-based compensation expense 285,000us-gaap_ShareBasedCompensation
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
9,000us-gaap_ShareBasedCompensation
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
                 
Share reserved for issue   252,752us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
252,752us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
            252,752us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
252,752us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
Exercisable weighted average price per share   $ 5.21us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
$ 5.21us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
            $ 5.21us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
$ 5.21us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
Stock option plan, Description Vest monthly over four years effective from their grant date.                    
Conversion of incentive award from liability to equity accounting               $ 121,000us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebt
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
     
Incentive Awards [Member] | Black-Scholes option pricing model [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Share based compensation arrangement by share based payment award, award vesting period   2 years                  
Incentive Awards [Member] | First Tranche [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Incentive awards vested percentage   100.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
/ us-gaap_PlanNameAxis
= cyma_IncentiveStockAwardsMember
/ us-gaap_VestingAxis
= us-gaap_ShareBasedCompensationAwardTrancheOneMember