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v3.19.3.a.u2

Leases - Additional Information (Detail) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($)
Lessee Disclosure [Abstract] |
Lease expiration date | Apr. 30, 2023
Lessee operating lease renewal term description | no stated renewal options
Operating lease expense | $ 0.6

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- Definition Lessee operating lease renewal term description. + References No definition available. + Details
Name: | cbio_LesseeOperatingLeaseRenewalTermDescription
Namespace Prefix: | cbio_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Date which lease or group of leases is set to expire, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_LeaseExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_LesseeDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of operating lease expense. Excludes sublease income. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918638-209977 + Details
Name: | us-gaap_OperatingLeaseExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration