v2.4.1.9

Warrants - Components of Common Stock Warrants Outstanding (Detail) (Common Stock [Member], USD $) | 12 Months Ended
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Dec. 31, 2013
Class of Warrant or Right [Line Items] |
Number of Shares Outstanding Underlying Warrants | 82,190us-gaap_ClassOfWarrantOrRightOutstanding
Class Of Warrant Or Right Issued on July 2006 [Member] |
Class of Warrant or Right [Line Items] |
Issue Date | 2006-07
Original Term | 10 years
Exercise Price | $ 31.72us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateFourMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Number of Shares Outstanding Underlying Warrants | 17,656us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateFourMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Class Of Warrant Or Right Issued on November 2006 [Member] |
Class of Warrant or Right [Line Items] |
Issue Date | 2006-11
Original Term | 10 years
Exercise Price | $ 31.72us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateFiveMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Number of Shares Outstanding Underlying Warrants | 1,576us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateFiveMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Class Of Warrant Or Right Issued on February 2008 [Member] |
Class of Warrant or Right [Line Items] |
Issue Date | 2008-02
Original Term | 10 years
Exercise Price | $ 35.07us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateSixMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Number of Shares Outstanding Underlying Warrants | 22,792us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateSixMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Class Of Warrant Or Right Issued on August 2009 [Member] |
Class of Warrant or Right [Line Items] |
Issue Date | 2009-08
Original Term | 10 years
Exercise Price | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateSevenMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Number of Shares Outstanding Underlying Warrants | 33,472us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateSevenMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Class Of Warrant Or Right Issued on July 2010 [Member] |
Class of Warrant or Right [Line Items] |
Issue Date | 2010-07
Original Term | 9 years
Exercise Price | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateEightMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Number of Shares Outstanding Underlying Warrants | 6,694us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateEightMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember

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- Definition Class of warrant or right warrant issuance month and year. + References No definition available. + Details
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Namespace Prefix: | cdna_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

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- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(4)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_ClassOfWarrantOrRightLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph i -Article 4 + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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- Definition Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssumptionsExpectedTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration