v2.4.1.9

Commitments and Contingencies - Additional Information (Detail) (USD $) | 12 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Sep. 30, 2014
Loss Contingencies [Line Items] |  |  |  |  |
Operating lease agreement expiry date | 2020-12 |  |  |  |
Rent expense under non-cancelable operating leases | $ 1,007,000us-gaap_OperatingLeasesRentExpenseNet | $ 1,020,000us-gaap_OperatingLeasesRentExpenseNet | $ 1,016,000us-gaap_OperatingLeasesRentExpenseNet |  |
Past due royalties | 0us-gaap_AccruedRoyaltiesCurrentAndNoncurrent | 2,804,000us-gaap_AccruedRoyaltiesCurrentAndNoncurrent |  |  |
Royalty revenues | 221,000us-gaap_RoyaltyRevenue | 94,000us-gaap_RoyaltyRevenue | 34,000us-gaap_RoyaltyRevenue |  |
July 1, 2011 through June 30, 2014 [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Settlement and payment | 2,800,000us-gaap_PaymentsForLegalSettlements / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember |  |  |  |
Decrease in cost of testing | 566,000cdna_IncreaseDecreaseInServicerPayables / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember |  |  |  |
Decrease in interest expense | 132,000us-gaap_IncreaseDecreaseInInterestPayableNet / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember |  |  |  |
Unpaid Royalties [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Settlement and mutual release agreement, counter party name | Roche |  |  |  |
Settlement and mutual release agreement, date | September 2014 |  |  |  |
Maximum number of days from end of calendar quarter for royalty payment | 45 days |  |  |  |
Settlement and mutual release agreement, terms of agreement | In September 2014, the Company entered into a settlement and mutual release agreement with Roche whereby: (i) for the period beginning July 1, 2011 through June 30, 2014, the Company agreed to pay the amount of $2,827,220 in settlement of past royalties due; (ii) for the period beginning July 1, 2014 through September 30, 2014, the Company agreed to pay royalties based on the same combination services percentage used to determine the past royalties due; (iii) for the period beginning October 1, 2014 through September 30, 2017, Roche and the Company agreed to a downward adjustment of the combination services percentage used to determine the portion of the AlloMap testing revenue that is royalty bearing under the terms of the license; (iv) the Company agreed to report and pay quarterly royalties within 45 days of the end of each calendar quarter; (v) Roche agreed that, subject to the Company’s timely payment of all applicable royalties through such date, no further royalties will be payable by the Company for periods after September 30, 2017; |  |  |  |
Royalty expenses | 650,000us-gaap_RoyaltyExpense / us-gaap_RelatedPartyTransactionAxis = cdna_RoyaltyAgreementLiabilityMember | 1,200,000us-gaap_RoyaltyExpense / us-gaap_RelatedPartyTransactionAxis = cdna_RoyaltyAgreementLiabilityMember | 1,100,000us-gaap_RoyaltyExpense / us-gaap_RelatedPartyTransactionAxis = cdna_RoyaltyAgreementLiabilityMember |  |
Unpaid Royalties [Member] | July 1, 2011 through June 30, 2014 [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Past due royalties |  |  |  |  | 2,827,220us-gaap_AccruedRoyaltiesCurrentAndNoncurrent / us-gaap_RelatedPartyTransactionAxis = cdna_RoyaltyAgreementLiabilityMember / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember
AlloMap [Member] | July 1, 2011 through June 30, 2014 [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Royalty revenues | $ 600,000us-gaap_RoyaltyRevenue / us-gaap_RelatedPartyTransactionAxis = cdna_AllomapMember / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember | $ 1,000,000us-gaap_RoyaltyRevenue / us-gaap_RelatedPartyTransactionAxis = cdna_AllomapMember / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember | $ 900,000us-gaap_RoyaltyRevenue / us-gaap_RelatedPartyTransactionAxis = cdna_AllomapMember / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember | $ 400,000us-gaap_RoyaltyRevenue / us-gaap_RelatedPartyTransactionAxis = cdna_AllomapMember / us-gaap_StatementScenarioAxis = cdna_ScenarioOneMember |

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