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Stock Incentive Plans - Summary of Option Activity and Related Information (Detail) (USD $)
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
| Shares Available for Grant, Beginning Balance | 332,995us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant | 180,266us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant | 306,188us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant |
| Shares Available for Grant, Additional options authorized | 940,884us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized | ||
| Number of Shares, Additional options authorized | 0cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesReservedForAvailableForIssuance | ||
| Weighted-average Exercise Price, Additional options authorized | $ 0.00cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageExercisedPriceSharesReserved | ||
| Shares Available for Grant, Granted | (585,345)cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantGrantedDuringPeriod | (4,081)cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantGrantedDuringPeriod | (211,056)cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantGrantedDuringPeriod |
| Shares Available for Grant, Assumed in business combination | 0cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAssumedInAcquisition | ||
| Shares Available for Grant, Exercised | 0cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExercised | 0cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExercised | 0cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExercised |
| Shares Available for Grant, Forfeited | 20,591cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeituresInPeriod | 7,247cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeituresInPeriod | 32,585cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeituresInPeriod |
| Shares Available for Grant, Expired | 13,781cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExpired | 149,563cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExpired | 52,549cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExpired |
| Shares Available for Grant, Ending Balance | 722,906us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant | 332,995us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant | 180,266us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant |
| Number of Shares, Beginning Balance | 466,965us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 619,906us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 496,908us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Number of Shares, Granted | 585,345us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross | 4,081us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross | 211,056us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross |
| Number of Shares, Assumed in business combination | 23,229cdna_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedFromAcquisitionsInPeriod | ||
| Number of Shares, Exercised | (9,363)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised | (212)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised | (2,924)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |
| Number of Shares, Forfeited | (20,591)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod | (7,247)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod | (32,585)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod |
| Number of Shares, Expired | (13,781)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod | (149,563)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod | (52,549)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod |
| Number of Shares, Ending Balance | 1,031,804us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 466,965us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 619,906us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Weighted-average Exercise Price, Beginning Balance | $ 1.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 2.67us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 3.70us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Weighted-average Exercise Price, Granted | $ 11.76us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice | $ 0.48us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice | $ 0.55us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice |
| Weighted-average Exercise Price, Assumed in business combination | $ 2.06cdna_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsSharesAssumedFromAcquisitionWeightedAverageExercisePrice | ||
| Weighted-average Exercise Price, Exercised | $ 2.14us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice | $ 0.55us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice | $ 3.36us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice |
| Weighted-average Exercise Price, Forfeited | $ 10.36us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice | $ 2.33us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice | $ 3.43us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice |
| Weighted-average Exercise Price, Expired | $ 2.74us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice | $ 4.73us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice | $ 3.49us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice |
| Weighted-average Exercise Price, Ending Balance | $ 7.36us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 1.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 2.67us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Increase In Number Of Shares Reserved For Available For Issuance No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Assumed In Acquisition No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Exercised No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Expired No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Forfeitures In Period No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Granted During Period No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Options Assumed From Acquisitions In Period No definition available.
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- Definition
Share Based Compensation Arrangement By Share Based Payment Award Weighted Average Exercised Price Shares Reserved No definition available.
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- Definition
Share Based Compensation Arrangements By Share Based Payment Award Options Shares Assumed From Acquisition Weighted Average Exercise Price No definition available.
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- Details
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- Definition
Number of additional shares authorized for issuance under an established share-based compensation plan. No definition available.
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- Definition
The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Gross number of share options (or share units) granted during the period. No definition available.
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- Definition
Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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- Definition
Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired. No definition available.
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- Definition
Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. No definition available.
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- Definition
Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
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- Definition
Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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