Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail)

v2.4.1.9
Summary of Significant Accounting Policies - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value $ 33,150us-gaap_AssetsFairValueDisclosure $ 27,940us-gaap_AssetsFairValueDisclosure
Total liabilities measured at fair value 13,596us-gaap_LiabilitiesFairValueDisclosure 6,919us-gaap_LiabilitiesFairValueDisclosure
Forward contract [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total liabilities measured at fair value   453us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ForwardContractsMember
Warrant liability [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total liabilities measured at fair value 13,596us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByLiabilityClassAxis
= cyma_WarrantLiabilityMember
6,466us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByLiabilityClassAxis
= cyma_WarrantLiabilityMember
Money market funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 9,941us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_MoneyMarketFundsMember
21,097us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_MoneyMarketFundsMember
Corporate debt and asset backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 23,209us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= cyma_CorporateDebtAndAssetBackedSecuritiesMember
6,843us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= cyma_CorporateDebtAndAssetBackedSecuritiesMember
Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 9,941us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
21,097us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Level 1 [Member] | Money market funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 9,941us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_MoneyMarketFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
21,097us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_MoneyMarketFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 23,209us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
6,843us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Level 2 [Member] | Corporate debt and asset backed securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total assets measured at fair value 23,209us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= cyma_CorporateDebtAndAssetBackedSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
6,843us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= cyma_CorporateDebtAndAssetBackedSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total liabilities measured at fair value 13,596us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
6,919us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Level 3 [Member] | Forward contract [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total liabilities measured at fair value   453us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ForwardContractsMember
Level 3 [Member] | Warrant liability [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total liabilities measured at fair value $ 13,596us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByLiabilityClassAxis
= cyma_WarrantLiabilityMember
$ 6,466us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByLiabilityClassAxis
= cyma_WarrantLiabilityMember