XML 43 R31.htm IDEA: XBRL DOCUMENT v3.19.2

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 93,438	$ 119,057
Gross Unrealized Gains	57	2
Gross Unrealized Losses		(6)
Estimated Fair Value	93,495	119,053
Money Market Funds | Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,858	29,090
Estimated Fair Value	16,858	29,090
Money Market Funds | Restricted cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	50	50
Estimated Fair Value	50	50
U.S. Government Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	57,870	74,144
Gross Unrealized Gains	34	1
Gross Unrealized Losses		(6)
Estimated Fair Value	57,904	74,139
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	16,858	30,089
Short-Term Investments
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	76,587	88,914
Federal Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,660
Gross Unrealized Gains	23
Estimated Fair Value	$ 18,683
Federal Agency Securities | Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		999
Estimated Fair Value		999
Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		14,774
Gross Unrealized Gains		1
Estimated Fair Value		$ 14,775

X

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=cbio_RestrictedCashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=us-gaap_AgencySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: