Name:	cbst_CollaborationAndLicenseAgreementMaximumPaymentsToBeReceivedUponAchievementOfDevelopmentRegulatoryAndCommercialMilestones
Namespace Prefix:	cbst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the payments made prior to acquisition under a collaboration and license agreement.

No definition available.

Name:	cbst_CollaborationAndLicenseAgreementPaymentsMadePriorToAcquisition
Namespace Prefix:	cbst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the percentage of future development costs required for global approval agreed to be reimbursed under a collaboration and license agreement.

No definition available.

Name:	cbst_CollaborationAndLicenseAgreementPercentageOfFutureDevelopmentCostsRequiredForGlobalApprovalAgreedToBeReimbursed
Namespace Prefix:	cbst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of future development costs required for local approval agreed to be reimbursed under a collaboration and license agreement.

No definition available.

Name:	cbst_CollaborationAndLicenseAgreementPercentageOfFutureDevelopmentCostsRequiredForLocalApprovalAgreedToBeReimbursed
Namespace Prefix:	cbst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the minimum period after the date of the first commercial sale over which royalties on annual net worldwide sales would be paid.

No definition available.

Name:	cbst_CollaborativeAndLicenseAgreementMinimumRoyaltyPeriod
Namespace Prefix:	cbst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the upfront payment made.

No definition available.

Name:	cbst_CollaborativeAndLicenseAgreementUpfrontPayment
Namespace Prefix:	cbst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of remaining milestone payments under license agreement.

No definition available.

Name:	cbst_RemainingMilestonePaymentsUnderLicenseAgreement
Namespace Prefix:	cbst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 17

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.