XML 58 R47.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value Measurements - Additional Information (Detail) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 USD ($) CommercialTest shares | Mar. 27, 2018 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2017 USD ($) shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Transfers between Level 1, Level 2 and Level 3 categories during the periods | $ 0 |  |  | $ 0
Change in estimated fair value of contingent consideration | $ 144,000 |  | $ (221,000) |
Change in fair market value of derivative liability |  | $ 2,500,000 | 800,000 |
ImmuMetrix, Inc. [Member] | Contingent Consideration Liability [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Contingent obligation to issue common stock | shares | 227,845 |  |  | 227,845
Milestone description | The issuance of shares will occur if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020. |  |  |
Number of commercial tests involving the measurement of cfDNA to be completed | CommercialTest | 2,500 |  |  |
Change in estimated fair value of contingent consideration | $ 100,000 |  | $ (200,000) |
ImmuMetrix, Inc. [Member] | Minimum [Member] | Contingent Consideration Liability [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Percentage of probability in achieving contingency condition | 80.00% |  |  |
ImmuMetrix, Inc. [Member] | Maximum [Member] | Contingent Consideration Liability [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |
Percentage of probability in achieving contingency condition | 100.00% |  |  |

X
- Definition Fair Value Measurements Inter Transfers Between Levels + References No definition available. + Details
Name: | cdna_FairValueMeasurementsInterTransfersBetweenLevels
Namespace Prefix: | cdna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of Commercial Tests + References No definition available. + Details
Name: | cdna_NumberOfCommercialTests
Namespace Prefix: | cdna_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of probability in achieving contingency condition. + References No definition available. + Details
Name: | cdna_PercentageOfProbabilityInAchievingContingencyCondition
Namespace Prefix: | cdna_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479 + Details
Name: | us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents a description of such arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessCombinationContingentConsiderationArrangementsDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Amount of unrealized gain (loss) recognized in the income statement for a financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + 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 (d) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cdna_ImmuMetrixIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=cdna_ContingentConsiderationLiabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |