v2.4.1.9

Warrants - Components of Convertible Preferred Stock Warrants Outstanding (Detail) (Series G Convertible Preferred Stock [Member], USD $) In Thousands, except Share data, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2013 | Apr. 30, 2012
Class of Warrant or Right [Line Items] |  |
Exercise Price |  | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Number of Shares of Outstanding Underlying Warrant | 541,613us-gaap_ClassOfWarrantOrRightOutstanding |
Estimated Fair Value as of December 31, 2013 | $ 525us-gaap_WarrantsNotSettleableInCashFairValueDisclosure |
Class Of Warrant Or Right Issued Date One [Member] |  |
Class of Warrant or Right [Line Items] |  |
Issue Date | 2010-12 |
Original Term | 7 years |
Exercise Price | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateOneMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Number of Shares of Outstanding Underlying Warrant | 17,215us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateOneMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Estimated Fair Value as of December 31, 2013 | 14us-gaap_WarrantsNotSettleableInCashFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateOneMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Class Of Warrant Or Right Issued Date Two [Member] |  |
Class of Warrant or Right [Line Items] |  |
Issue Date | 2012-04 |
Original Term | 5 years |
Exercise Price | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateTwoMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Number of Shares of Outstanding Underlying Warrant | 357,216us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateTwoMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Estimated Fair Value as of December 31, 2013 | 218us-gaap_WarrantsNotSettleableInCashFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateTwoMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Class Of Warrant Or Right Issued Date Three [Member] |  |
Class of Warrant or Right [Line Items] |  |
Issue Date | 2012-08 |
Original Term | 7 years |
Exercise Price | $ 21.78us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateThreeMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Number of Shares of Outstanding Underlying Warrant | 167,182us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateThreeMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |
Estimated Fair Value as of December 31, 2013 | $ 293us-gaap_WarrantsNotSettleableInCashFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = cdna_ClassOfWarrantOrRightIssuedDateThreeMember / us-gaap_StatementClassOfStockAxis = cdna_SeriesGConvertiblePreferredStockMember |

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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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Definition Fair value portion of warrants not settleable in cash classified as equity. + 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 (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsNotSettleableInCashFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant