CareDx (CDNA) 10-Q 9 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 06, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	CDNA
Entity Registrant Name	CareDx, Inc.
Entity Central Index Key	1,217,234
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		36,346,124

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 16,246,000	$ 16,895,000
Accounts receivable	8,072,000	2,991,000
Inventory	4,666,000	5,529,000
Prepaid and other assets	1,593,000	1,352,000
Total current assets	30,577,000	26,767,000
Property and equipment, net	2,360,000	2,075,000
Intangible assets, net	34,760,000	33,139,000
Goodwill	12,005,000	12,005,000
Restricted cash	177,000	9,579,000
Total assets	79,879,000	83,565,000
Current liabilities:
Accounts payable	3,480,000	3,391,000
Accrued payroll liabilities	5,576,000	5,013,000
Accrued and other liabilities	4,703,000	3,735,000
Deferred revenue	39,000	39,000
Deferred purchase consideration	378,000	407,000
Derivative liability	0	14,600,000
Current debt	0	15,721,000
Total current liabilities	14,176,000	42,906,000
Deferred rent, net of current portion	686,000	913,000
Deferred revenue, net of current portion	711,000	730,000
Deferred tax liability	3,693,000	4,933,000
Long-term debt, net of current portion	13,337,000	18,338,000
Contingent consideration	0	1,672,000
Common stock warrant liability	16,800,000	18,712,000
Other liabilities	1,524,000	1,315,000
Total liabilities	50,927,000	89,519,000
Commitments and contingencies (Note 8)	0	0
Stockholders’ equity:
Preferred stock: $0.001 par value; 10,000,000 shares authorized at June 30, 2018 and December 31, 2017; no shares issued and outstanding at June 30, 2018 and December 31, 2017	0	0
Common stock: $0.001 par value; 100,000,000 shares authorized at June 30, 2018 and December 31, 2017; 35,975,493 shares and 28,825,019 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	36,000	29,000
Additional paid-in capital	321,144,000	264,204,000
Accumulated other comprehensive loss	(4,108,000)	(2,345,000)
Accumulated deficit	(288,120,000)	(268,022,000)
Total CareDx, Inc. stockholders' equity (deficit)	28,952,000	(6,134,000)
Noncontrolling interest	0	180,000
Total stockholders’ equity (deficit)	28,952,000	(5,954,000)
Total liabilities and stockholders’ equity	$ 79,879,000	$ 83,565,000

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	35,975,493	28,825,019
Common stock, shares outstanding	35,975,493	28,825,019

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operation - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Total revenue	$ 17,823	$ 12,046	$ 31,876	$ 23,630
Operating expenses:
Research and development	3,496	3,118	6,864	6,401
Sales and marketing	5,860	3,270	9,945	6,492
General and administrative	5,596	4,132	10,903	10,634
Goodwill impairment	0	0	0	1,958
Change in estimated fair value of contingent consideration	873	(64)	1,017	(285)
Total operating expenses	23,032	15,645	42,320	35,773
Loss from operations	(5,209)	(3,599)	(10,444)	(12,143)
Interest expense	(424)	(1,691)	(3,119)	(2,481)
Other expense, net	(42)	(188)	(2,851)	(874)
Change in estimated fair value of common stock warrant liability and derivative liability	(8,768)	1,067	(7,447)	5,195
Loss before income taxes	(14,443)	(4,411)	(23,861)	(10,303)
Income tax benefit	381	376	805	659
Net loss	(14,062)	(4,035)	(23,056)	(9,644)
Net loss attributable to noncontrolling interest	0	(67)	(25)	(114)
Net loss attributable to CareDx, Inc.	$ (14,062)	$ (3,968)	$ (23,031)	$ (9,530)
Net loss per share attributable to CareDx, Inc. (Note 3):
Basic	$ (0.40)	$ (0.19)	$ (0.71)	$ (0.45)
Diluted	$ (0.40)	$ (0.19)	$ (0.71)	$ (0.45)
Weighted average shares used to compute net loss per share attributable to CareDx, Inc.:
Basic	35,549,837	21,412,480	32,599,032	21,378,321
Diluted	35,549,837	21,412,480	32,599,032	21,378,321
Testing Services [Member]
Revenue:
Total revenue	$ 13,997	$ 8,420	$ 24,601	$ 16,322
Operating expenses:
Cost of testing services and product	4,568	3,011	8,680	6,068
Product [Member]
Revenue:
Total revenue	3,550	3,376	6,857	7,043
Operating expenses:
Cost of testing services and product	2,639	2,178	4,911	4,505
License and Other [Member]
Revenue:
Total revenue	$ 276	$ 250	$ 418	$ 265

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (14,062)	$ (4,035)	$ (23,056)	$ (9,644)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(1,625)	670	(1,762)	934
Total comprehensive loss	(15,687)	(3,365)	(24,818)	(8,710)
Comprehensive loss attributable to noncontrolling interest, net of tax	0	(72)	(25)	(124)
Comprehensive loss attributable to CareDx, Inc.	$ (15,687)	$ (3,293)	$ (24,793)	$ (8,586)

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net loss	$ (23,056)	$ (9,644)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,025	1,821
Amortization of inventory fair market value adjustment	189	170
Loss on conversion of JGB debt to shares of common stock	2,806	0
Amortization of debt discount and noncash interest expense	2,132	1,769
Revaluation of common stock warrant liability and derivative liability to estimated fair value	7,447	(5,195)
Stock-based compensation	3,217	886
Revaluation of contingent consideration to estimated fair value	1,017	(285)
Goodwill impairment	0	1,958
Changes in operating assets and liabilities:
Accounts receivable	(2,280)	(152)
Inventory	333	252
Prepaid and other assets	(296)	(189)
Accounts payable	195	422
Accrued payroll liabilities	686	(486)
Accrued and other liabilities	92	(710)
Change in deferred revenue	(19)	(12)
Change in deferred taxes	(892)	(542)
Net cash used in operating activities	(6,404)	(9,937)
Investing activities:
Purchase of property and equipment	(461)	(94)
Net cash used in investing activities	(6,355)	(94)
Financing activities:
Proceeds from debt, net of issuance costs	14,282	24,002
Proceeds from issuance of common stock under employee stock purchase plan	32	44
Principal payments on debt and capital lease obligations	(11,349)	(12,871)
Change in short term credit facility	(677)	176
Proceeds from exercise of warrants	524	0
Repurchases of common stock under employee incentive plans	(142)	0
Proceeds from exercise of stock options	179	0
Net cash provided by financing activities	2,758	11,351
Effect of exchange rate changes on cash and cash equivalents	(50)	(64)
Net increase (decrease) in cash, cash equivalents and restricted cash	(10,051)	1,256
Cash, cash equivalents, and restricted cash at beginning of period	26,474	17,401
Cash, cash equivalents, and restricted cash at end of period	16,423	18,657
Supplemental disclosure of cash flow information:
Deferred purchase consideration	0	1,064
Contingent consideration shares issued	2,689	0
Illumina [Member]
Investing activities:
Acquisition of intangible assets through Illumina Licensing Agreement	(5,202)	0
Allenex AB [Member]
Investing activities:
Acquisition of Allenex AB minority interest	(692)	0
Conexio [Member]
Financing activities:
Acquisition of business, net of cash acquired	$ (91)	$ 0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash, Cash Equivalents and Restricted Cash as of:
Cash and cash equivalents	$ 16,246	$ 16,895
Restricted cash	177	9,579
Total cash, cash equivalents and restricted cash at the end of period	$ 16,423	$ 26,474

Organization and Description of

Organization and Description of Business	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Description of Business	1. ORGANIZATION AND DESCRIPTION OF BUSINESS CareDx, Inc. (“CareDx” or the “Company”) together with its subsidiaries, is a global transplant diagnostics company with product offerings along the pre- and post-transplant continuum. The Company focuses on discovery, development and commercialization of clinically differentiated, high-value diagnostic surveillance solutions for transplant patients. In diagnostic testing services, the Company offers AlloMap®, which is a gene expression solution for heart transplant patients and AlloSure®, which is a donor-derived cell free DNA (“dd-cfDNA”) solution initially used for kidney transplant patients. The Company also offers high quality products that increase the chance of successful transplants by facilitating a better match between a donor and a recipient of stem cells and organs. AlloMap is a gene expression test that helps clinicians monitor and identify heart transplant recipients with stable graft function who have a low probability of moderate to severe acute cellular rejection. Since 2008, the Company has sought to expand the adoption and utilization of its AlloMap solution through ongoing studies to substantiate the clinical utility and actionability of AlloMap, secure positive reimbursement decisions for AlloMap from large private and public payers, develop and enhance its relationships with key members of the transplant community, including opinion leaders at major transplant centers, and explore opportunities and technologies for the development of additional solutions for post-transplant surveillance. The Company believes the use of AlloMap, in conjunction with other clinical indicators, can help healthcare providers and their patients better manage long-term care following a heart transplant. In particular, the Company believes AlloMap can improve patient care by helping healthcare providers avoid the use of unnecessary, invasive surveillance biopsies and determine the appropriate dosage levels of immunosuppressants. AlloMap has received 510(k) clearance from the U.S. Food and Drug Administration (the “FDA”) for marketing and sale as a test to aid in the identification of recipients with a low probability of moderate or severe acute cellular rejection. A 510(k) submission is a premarketing submission made to the FDA. Clearance may be granted by the FDA if it finds the device or test provides satisfactory evidence pertaining to the claimed intended uses and indications for the device or test. On October 9, 2017, the Company commercially launched AlloSure, its proprietary next-generation sequencing-based test to measure dd-cfDNA after transplantation. The Company believes the use of AlloSure, in conjunction with other clinical indicators, can help healthcare providers and their patients better manage long-term care following a kidney transplant. In particular, the Company believes AlloSure can improve patient care by helping healthcare providers to reduce the use of invasive biopsies and determine the appropriate dosage levels of immunosuppressants. The Company also develops, manufactures, markets and sells products that increase the chance of successful transplants by facilitating a better match between a donor and a recipient of stem cells and organs. Olerup SSP® is used to type Human Leukocyte Antigen (“HLA”) alleles, based on the sequence specific primer (“SSP”) technology. Olerup SBT TM precision in HLA typing at a low to intermediate resolution for samples that require a fast turn-around-time On May 4, 2018, the Company entered into a License and Commercialization Agreement with Illumina, Inc. (“Illumina”), which provides the Company with worldwide distribution, development and commercialization rights to Illumina’s next generation sequencing (“NGS”) product line for use in transplantation diagnostic testing. The Company’s headquarters are in Brisbane, California; primary operations are in Brisbane, U.S. and Stockholm, Sweden; and the Company operates in two reportable segments. Liquidity and Going Concern The Company has incurred significant losses and negative cash flows from operations since its inception and had an accumulated deficit of $288.1 million at June 30, 2018. As of June 30, 2018, the Company had cash and cash equivalents of $16.2 million, and $13.3 million On April 17, 2018, the Company entered into a credit agreement with Perceptive Credit Holdings II, LP (“Perceptive ”) The Company may req uire additional financing in the future to fund working capital and pay its obligations as they come due. Additional financing might include issuance of equity securities, debt, cash from collaboration agreements or a combination of these. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The significant accounting policies and estimates used in preparation of the unaudited condensed consolidated financial statements are described in the Company’s audited consolidated financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K. Material changes to the significant accounting policies previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 are reflected below. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”), and follow the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments that are necessary for a fair statement of the Company’s financial information. The condensed consolidated balance sheet as of December 31, 2017 has been derived from audited financial statements as of that date but does not include all of the financial information required by U.S. GAAP for complete financial statements. Operating results for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany transactions have been eliminated. The Company acquired CareDx International AB, formerly Allenex AB “Allenex”, on April 14, 2016. Since the acquisition of Allenex through March 15, 2018, the Company owned less than 100% of the shares of Allenex and recorded a net loss attributable to noncontrolling interest in its condensed consolidated statements of operations equal to the percentage of the economic or ownership interest retained by the respective noncontrolling parties in such entities. On March 15, 2018, the Company acquired the remaining noncontrolling interest in Allenex and has not reported any noncontrolling interest balances since this date. Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the unaudited condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to (i) variable transaction price consideration related to contracts with customers, (ii) the determination of the accruals for clinical studies, (iii) the fair value of assets and liabilities acquired in business combinations, including contingent consideration, (iv) inventory valuation, (v) the valuation of common stock warrant liability, (vi) the fair value of embedded derivatives, (vii) measurement of stock-based compensation expense, (viii) the determination of the valuation allowance and estimated tax benefit associated with deferred tax assets and net deferred tax liability, (ix) any impairment of long-lived assets, including in-process technology and goodwill, and (x) legal contingencies. Actual results could differ from those estimates. Concentrations of Credit Risk and Other Risks and Uncertainties For the six months ended June 30, 2018 and 2017, approximately 45% and 28%, respectively, of total revenue was derived from Medicare. No other payers or customers represented more than 10% of total revenue for these periods. At June 30, 2018 and December 31, 2017, approximately 24% and 16%, respectively, of accounts receivable was due from Medicare. No other payer or customer represented more than 10% of accounts receivable on either June 30, 2018 or December 31, 2017. Restricted Cash A restricted cash balance of $9.4 million was released upon the full conversion of the debt obligation to JGB Collateral LLC and certain of its affiliates (“JGB”) (refer to Note 10) during the three months ended March 31, 2018 and is no longer classified as restricted cash. As a condition of the lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements and a surety bond. These agreements are collateralized by cash. The cash used to support these arrangements is classified as long-term restricted cash on the accompanying condensed consolidated balance sheets. Common Stock Warrant Liability and Derivative Liability Common Stock Warrant Liability On January 1, 2018, the Company adopted Accounting Standard Update (“ASU”) No. 2017-11, Accounting for Certain Financial Instruments with Down Round Features and Replacement of the Indefinite Deferral of Mandatorily Redeemable Financial Instruments of Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. Derivative Liability The convertible debt financing with JGB (the “JGB Debt”), included certain embedded derivatives that required bifurcation, including settlement and penalty provisions. The combined embedded derivative was remeasured at each reporting period with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations. As of March 27, 2018, the JGB Debt was fully converted to shares of the Company’s common stock. The change in the fair market value of the derivative liability through March 27, 2018 was recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations. On April 17, 2018, the Company entered into the Perceptive Credit Agreement, which included an embedded derivative that required bifurcation related to early repayment provision. This embedded derivative fair value of $0.2 million was recorded as debt issuance discount. Refer to Note 10 for additional details. The derivative is remeasured at the end of each reporting period if debt remains outstanding with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations. Revenue The Company recognizes revenue from testing services, products, and license and other revenue in the amount that reflects the consideration which it expects to be entitled in exchange for goods or services as it transfers control to its customers. Revenue is recorded considering a five-step model that includes identifying the contract with a customer, identifying the performance obligations in the contract, determining the transaction price, allocating the transaction price to the performance obligations, and recognizing revenue when, or as, an entity satisfies a performance obligation. Testing Services Revenue AlloMap and AlloSure patient tests are ordered by healthcare providers. The Company receives a test requisition form with payer information along with a collected patient blood sample. The Company considers the patient to be its customer and the test requisition form a contract. Testing services are performed in the Company’s laboratory. Testing services represent one performance obligation in a contract and are performed when results of the test are provided to the healthcare provider, at a point of time. The healthcare providers that order the tests and on whose behalf CareDx provides testing services are generally not responsible for the payment of these services. The first and second revenue recognition criteria are satisfied when the Company receives a test requisition form with payer information from the healthcare provider. Generally, the Company bills third-party payers upon delivery of an AlloMap or AlloSure test result to the healthcare provider. Amounts received may vary amongst payers based on coverage practices and policies of the payer. The Company has used the portfolio approach, a practical expedient under Accounting Standards Codifications (“ASC”) Topic 606, to identify financial classes of payers. Transaction prices are determined for each financial class using history of reimbursements, including analysis of an average reimbursement per test and a percentage of tests reimbursed. The Company estimates revenue for non-contracted payers and self-payers using this methodology. The estimate requires significant judgment. Revenue recognized for Medicare and other contracted payers is based on the agreed current reimbursement rate per test, adjusted for historical collection trends where applicable. The Company monitors revenue estimates at each reporting period based on actual cash collections in order to assess whether a revision to the estimate is required. Changes in transaction price estimates are updated quarterly based on actual cash collected or changes made to contracted rates. Product Revenue Product revenue is recognized from the sale of products to end-users, distributors and strategic partners when all revenue recognition criteria are satisfied. The Company generally has a contract or a purchase order from a customer with the specified required terms of order, including the number of products ordered. Transaction prices are determinable and products are delivered and risk of loss passed to the customer upon either shipping or delivery, as per the terms of the agreement. There are no further performance obligations related to a contract and revenue is recognized at the point of delivery consistent with the terms of the contract or purchase order. License and Other Revenue The Company generates revenue from license agreements. License agreements may include non-refundable upfront payments, partial or complete reimbursement of research and development costs, contingent payments based on the occurrence of specified events under the agreements, license fees and royalties on sales of products or product candidates if they are successfully commercialized. The Company’s performance obligations under the agreements may include the transfer of intellectual property rights in the form of licenses, obligations to provide research and development services and obligations to participate on certain development committees. The Company makes judgments to determine if performance obligations are distinct or should be combined and the transaction price allocated to each performance obligation, which affect the periods over which revenue is recognized. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any change in estimated periods of performance on a prospective basis. The Company constrains variable consideration, such as milestones, if it is probable that a significant portion of revenue would be reversed. The Company’s deferred revenue relates to one performance obligation, which should be recognized over time. The Company did not recognize any revenue connected with milestones during the three or six months ended June 30, 2018 or 2017. Cost of Testing Services Cost of testing services reflects the aggregate costs incurred in delivering the Company’s testing services. The components of cost of testing are materials and service costs, direct labor costs, stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples, and allocated overhead including rent, information technology, equipment depreciation, utilities and royalties. Prior to adoption of the new revenue guidance, the Company recorded costs of testing associated with performing tests (except royalties) in the period when tests were performed without consideration of whether revenue was recognized in the same period. With the adoption of the new revenue standard on January 1, 2018, revenue and cost of testing for tests performed are recognized in the same period. Royalties for licensed technology, calculated as a percentage of test revenues, are recorded as license fees in cost of testing services at the time the test revenues are recognized. Recent Accounting Pronouncements On January 1, 2018, the Company adopted the new revenue accounting standard Revenue from Contracts with Customers (Topic 606) The adoption of ASC 606 resulted in a one-time adjustment of $2.9 million to accounts receivable and retained earnings on January 1, 2018. The adjustment reflects the estimated payments to be received for tests where the result had been delivered at December 31, 2017, but associated revenue had not been recognized by December 31, 2017, because payment had not been received. The new standard did not impact the Company’s product revenue or license and other revenue, nor did it impact contract assets or contract liabilities. The following table summarizes the impact of the ASC 606 adoption on accounts receivable as of June 30, 2018 (in thousands): Balance as Reported Balance without the adoption of ASC 606 Impact of Adoption of ASC 606 Balance Sheets Accounts Receivable $ 8,072 $ 4,564 $ 3,508 The following table summarizes the impact to the statement of operations in accordance with the new revenue standard requirements for the three and six months ended June 30, 2018 (in thousands): Three Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 13,997 $ 13,484 $ 513 Product revenue 3,550 3,550 — License and other revenue 276 276 — $ 17,823 $ 17,310 $ 513 Six Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 24,601 $ 24,076 $ 525 Product revenue 6,857 6,857 — License and other revenue 418 418 — $ 31,876 $ 31,351 $ 525 In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (Topic 842), Codification Improvements to Topic 842, Leases. Leases (Topic 842): Targeted Improvements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force) . In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting In July 2017, the FASB issued ASU No. 2017-11, Accounting for Certain Financial Instruments with Down Round Features and Replacement of the Indefinite Deferral of Mandatorily Redeemable Financial Instruments of Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception In February 2018, the FASB issued ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share Based Payment Accounting

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	3. NET LOSS PER SHARE Basic and diluted net loss per share have been computed by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of common share equivalents as their effect would have been antidilutive. The following tables set forth the computation of the Company’s basic and diluted net loss per share (in thousands, except shares and per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator: Net loss attributable to CareDx, Inc. used to compute basic and diluted net loss per share $ (14,062 ) $ (3,968 ) $ (23,031 ) $ (9,530 ) Denominator: Weighted-average shares used to compute basic and diluted net loss per share attributable to CareDx, Inc. 35,549,837 21,412,480 32,599,032 21,378,321 Net loss per share attributable to CareDx, Inc.: Basic and diluted $ (0.40 ) $ (0.19 ) $ (0.71 ) $ (0.45 ) The following potentially dilutive securities have been excluded from diluted net loss per share, because their effect would be antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Shares of common stock subject to outstanding options 2,561,458 1,898,389 2,561,458 1,898,389 Shares of common stock subject to outstanding common stock warrants 3,328,089 4,509,926 3,328,089 4,509,926 Shares of common stock subject to convertible notes — 6,092,105 — 6,092,105 Shares of common stock subject to contingent consideration — 227,845 — 227,845 Restricted stock units 896,904 353,807 896,904 353,807 Total common stock equivalents 6,786,451 13,082,072 6,786,451 13,082,072 On October 10, 2017, the Company completed an underwritten public offering (the “2017 Public Offering”), pursuant to which the Company issued and sold an aggregate of 4,992,840 shares. During 2017 and the three months ended March 31, 2018, 6,415,039 shares of common stock subject to convertible notes were issued due to the conversion of the JGB Debt. In the three months ended June 30, 2018, the Company achieved the milestone of performing 2,500 commercial AlloSure tests; therefore, the Company issued 227,845 shares of common stock to the former owners of ImmuMetrix, Inc. (“IMX”) that was previously considered contingent consideration. The Perceptive Credit Agreement includes a Tranche B loan of $10.0 million available at the Company’s option at any time from April 17, 2018 to April 17, 2019 (the “Tranche B Term Loan”). If the Tranche B Term Loan is funded, the Company will issue to Perceptive an additional warrant to purchase up to 93,333 shares of common stock.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. FAIR VALUE MEASUREMENTS The Company records its financial assets and liabilities at fair value except for its debt, which was recorded at amortized cost. The carrying amounts of certain financial instruments of the Company, including cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: • Level 1: Inputs which include quoted prices in active markets for identical assets and liabilities. • Level 2: Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The following table sets forth the Company’s financial assets and liabilities measured at fair value on a recurring basis, as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 12,958 $ — $ — $ 12,958 Liabilities Common stock warrant liability — — 16,800 16,800 Perceptive derivative liability — — 235 235 Total liabilities $ — $ — $ 17,035 $ 17,035 December 31, 2017 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 13,097 $ — $ — $ 13,097 Liabilities Contingent consideration $ — $ — $ 1,672 $ 1,672 Common stock warrant liability — — 18,712 18,712 JGB derivative liability — — 14,600 14,600 Total liabilities $ — $ — $ 34,984 $ 34,984 The following table presents the issuances, changes in fair value and reclassifications of the Company’s Level 3 financial instruments that are measured at fair value on a recurring basis (in thousands): (Level 3) Contingent Consideration Liability Common JGB Derivative Liability Perceptive Derivative Liability Total Balance as of December 31, 2017 $ 1,672 $ 18,712 $ 14,600 — $ 34,984 Exercise of warrants — (127 ) — — (127 ) Conversion of JGB debt to common stock (Note 10) — — (12,066 ) — (12,066 ) Reclassification to equity (Note 2) — (6,550 ) — — (6,550 ) Issuance of Perceptive derivative liability — — — 235 235 Change in estimated fair value (1,672 ) 4,765 (2,534 ) — 559 Balance as of June 30, 2018 $ - $ 16,800 $ — $ 235 $ 17,035 The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers between Level 1, Level 2 and Level 3 categories during the periods presented. In determining fair value, the Company uses various valuation approaches within the fair value measurement framework. The valuation methodologies used for the Company’s instruments measured at fair value and their classification in the valuation hierarchy are summarized below: • Money market funds - Investments in money market funds are classified within Level 1. At June 30, 2018 and December 31, 2017, money market funds were included on the balance sheets in cash and cash equivalents. • Perceptive Credit Agreement - The Company has recorded its debt with Perceptive at carrying value. The fair value is consistent with its carry value of $13.3 million as of June 30, 2018. • Contingent consideration liability - As of December 31, 2017, the Company had a contingent obligation to issue 227,845 shares of the Company’s common stock to the former owners of IMX in conjunction with its acquisition of IMX in June 2014. The shares were issuable upon the Company completing 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020. The fair value of the contingent consideration is estimated using the closing market price of the common stock multiplied by management’s estimate of the probability of achievement of the contingency condition disclosed above, as of each period end. The probability of achievement of a contingency condition was a significant input in the Level 3 measurement and was 100% in presented periods. Increases (decreases) in the estimation of the probability percentage resulted in a directionally similar impact to the fair value of the contingent consideration liability. The Company achieved the contingent consideration milestone of 2,500 commercial tests and issued the 227,845 shares in the three months ended June 30, 2018. There is no contingent consideration outstanding at June 30, 2018. • Common stock warrant liability – The Company utilizes a binomial-lattice pricing model (the “Monte Carlo Simulation Model”) that involves a market condition simulation to estimate the fair value of the warrants. The application of the Monte Carlo Simulation Model requires the use of a number of complex assumptions including the Company’s stock price, expected life of the warrants, stock price volatility determined from the Company’s historical stock prices and stock prices of peer companies in the diagnostics industry, and risk-free rates based on the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected life of the warrants. Increases (decreases) in the assumptions discussed above result in a directionally similar impact to the fair value of the common stock warrant liability. • JGB Debt derivative liability – The Company utilized the Monte Carlo Simulation Model to estimate the fair value of the compound derivative liability recorded in connection with the JGB Debt. The Monte Carlo Simulation Model used multiple input assumptions to simulate the likelihood that market conditions will be achieved through 100,000 random trials. These assumptions included the expected term of the embedded derivative, the volatility of the Company’s stock prices and its peers’ stock prices over such expected term, likelihood, timing, and amount of future equity financing rounds, the likelihood of any prepayment or default events, the likelihood of monthly redemptions by the JGB Debt holders, and the likelihood and ability of JGB to convert the debt into equity. In each iteration of the simulations these assumptions were used to simulate the Company’s stock price drawing from a risk neutral distribution, the occurrence of a conversion event, the occurrence of a prepayment event, the occurrence of a default event, and any resulting payoff from such event. The average present value over all iterations of the simulation was then calculated. Increases (decreases) in the assumptions discussed above result in a directionally similar impact to the fair value of the derivative liability. The assumptions used in this simulation model were reviewed on a quarterly basis and adjusted, as needed. For the six months ended June 30, 2017 and from January 1, 2018 to March 27, 2018, the Company recorded the changes in fair value of the derivative liability of $1.3 million income and of $2.5 million income, respectively, in the change in estimated value of common stock warrant liability and derivative liability in its condensed consolidated statements of operations. The derivative liability was re-measured and fully extinguished upon the final JGB Debt conversion on March 27, 2018 (see Note 10). • Perceptive Credit Agreement derivative liability – The Company used a net present value analysis to estimate the fair value of the embedded derivative liability recorded in connection with the Perceptive Credit Agreement. The assumptions used in the analysis were the discount rate, the probability of early repayment during the term of the Credit Agreement and the expected term of the derivative. An increase in the discount rate will result in a decrease in liability and an increase in the probability of early repayment will result in an increase in liability. The assumptions used in this analysis will be reviewed on a quarterly basis and adjusted, as needed. For the three months ended June 30, 2018, the Company recorded the changes in fair value of the derivative liability of less than $0.1 million income in the change in estimated value of common stock warrant liability and derivative liability in its condensed consolidated statements of operations. Common Stock Warrant Liability and Derivative Liability Valuation Assumptions June 30, 2018 December 31, 2017 Private Placement Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 1.12 $ 1.12 Remaining term (in years) 4.79 5.29 Volatility 75.00 % 66.00 % Risk-free interest rate 2.68 % 2.21 % Subsequent Financing Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 4.00 $ 4.00 Remaining term (in years) 4.96 5.46 Volatility 75.00 % 65.00 % Risk-free interest rate 2.69 % 2.21 % Placement Agent Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 1.12 $ 1.12 Remaining term (in years) 2.79 3.29 Volatility 87.00 % 82.00 % Risk-free interest rate 2.57 % 1.99 % Perceptive Derivative Liability Remaining term (in years) 4.80 — Discount rate 7.50 % — % JGB Common Stock Warrant Liability Stock Price — $ 7.34 Exercise Price — $ 4.67 Remaining term (in years) — 4.71 Volatility — % 69.00 % Risk-free interest rate — % 1.89 % JGB Derivative Liability Stock Price — $ 7.34 Remaining term (in years) — 2.16 Volatility — % 69.00 % Risk-free interest rate — % 2.14 %

Business Combinations and Asset

Business Combinations and Asset Acquisitions	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Business Combinations and Asset Acquisitions	5. BUSINESS COMBINATIONS AND ASSET ACQUISITIONS Business Combinations Allenex On April 14, 2016, the Company acquired 98.3% of the outstanding common stock of Allenex, a transplant diagnostic company based in Stockholm, Sweden that developed, manufactured and sold products that help match donor organs with potential recipients prior to transplantation. Allenex had a presence and direct distribution channels in the United States and Europe, with additional third party distributors in Europe and other markets around the world. Under the terms of the Conditional Share Purchase Agreements entered into on December 16, 2015, as amended, and the tender offer prospectus dated March 7, 2016, and as a result of the tender offer, the aggregate purchase consideration paid by the Company was approximately $34.1 million and consisted of (i) $26.9 million of cash, of which $5.7 million (which represents SEK 50,620,000 as of the acquisition date) was deferred purchase consideration originally payable to Midroc Invest AB, FastPartner AB and Xenella Holding AB, the former majority shareholders of Allenex (the “Former Majority Shareholders”) by no later than March 31, 2017, subject to certain contingencies being met, and (ii) the issuance of 1,375,029 shares of the Company’s common stock valued at $7.2 million. Of the total cash consideration, $8.0 million of cash payable to the Former Majority Shareholders was deposited into an escrow account by the Company and subsequently invested in the Company by the Former Majority Shareholders through a purchase of the Company’s equity securities in a private placement. Upon the completion of such private placement, certain contingencies in the Conditional Share Purchase Agreements were waived. On June 8, 2016, the Company delisted Allenex’s common stock from Nasdaq Stockholm. The date by which the deferred purchase consideration was due to the Former Majority Shareholders was subsequently extended to July 1, 2017. In addition, interest began accruing on the Company’s obligations to the Former Majority Shareholders (the “Deferred Obligation”) at a rate of 10.0% per year commencing on January 1, 2017. On July 1, 2017, the Deferred Obligation totaled $6.3 million. On July 1, 2017, the Conditional Share Purchase Agreements were amended The Company has accounted for the Allenex transaction as a business combination in exchange for total consideration of approximately $34.1 million. Under business combination accounting, the total purchase price was allocated to Allenex’s net tangible and identifiable intangible assets based on their estimated fair values as of April 14, 2016. The fair value of the remaining 1.7% of noncontrolling interest in Allenex was purchased on March 15, 2018. The fair value of the noncontrolling interest was determined based on the number of outstanding shares comprising the noncontrolling interest and Allenex’s stock price of SEK 2.48 per share as of the acquisition date. The noncontrolling interest was presented as a component of stockholders’ equity on the Company’s condensed consolidated balance sheets at December 31, 2017. Conexio On January 20, 2017, the Company acquired the business assets of Conexio Genomics Pty. Ltd (“Conexio”). Prior to the acquisition, the Company was the exclusive distributor of the Conexio SBT TM Asset Acquisition Illumina License and Commercialization Agreement On May 4, 2018, the Company entered into a License and Commercialization Agreement (the “License Agreement”) with Illumina, which provides the Company with certain worldwide distribution, development and commercialization rights to Illumina’s NGS product line for use in the field of bone marrow and solid organ transplantation diagnostic testing (the “Field”). As a result, The License Agreement required the Company to make a $5.0 million initial cash payment to Illumina and further requires the Company to pay royalties in the mid-single to low-double digits on sales of future commercialized products. Pursuant to the License Agreement, the Company is obligated to complete timely development and commercialization of other NGS product lines for use in the Field, and has agreed to minimum purchase commitments of finished products and raw materials from Illumina through 2023. As the License Agreement did not meet the definition of a business combination under FASB ASC Topic 805, Business Combinations, Costs relating to the assets acquired were $5.2 million, comprising of the cash consideration of $5.0 million and associated transaction costs of $0.2 million. A deferred tax balance was not required to be established on the License Agreement date as the book and tax basis of the intangible assets was equivalent to the amount paid. The allocation of the purchase price to identified intangible assets acquired was based on the Company's best estimate of the fair value of such assets as of the acquisition date. Significant assumptions utilized in the valuation of identified intangible assets were based on company specific information and projections, which are not observable in the market and are thus considered Level 3 measurements as defined by U.S. GAAP. Customer relationships represent the fair value of future projected revenue that is expected to be derived from sales of TruSight HLA products to existing customers of Illumina. The customer contracts and related relationships value has been estimated utilizing a multi-period excess earnings method under income approach, which reflects the present value of the projected cash flows that are expected to be generated by the customer relationships less charges representing the contribution of other assets to those cash flows that use projected cash flows with and without the intangible asset in place. The economic useful life was determined based on the life of the products, assuming that the existing customers will remain with the Company until the products becomes obsolete. The Company utilized a discount rate of 18% in estimating the fair value of the customer relationships. The acquired in-process technology represents the fair value of products in development that have not reached commercial production at the date of acquisition. The fair value of the products was also determined using the multi-period excess earnings method under income approach. A rate of 30% and 40% for the AlloSeq HLA acquired in-process technology and the AlloSeq BMT acquired in-process technology, respectively, was utilized to discount the cash flows to the present value. The acquired in-process technology will not be amortized until completion of the related products, which is determined by when the products commence commercial production. Upon completion, each acquired in-process technology product will be amortized over its estimated useful life. The following table summarizes the fair values of the intangible assets acquired as of the closing date (in thousands): Estimated Fair Value Estimated Useful Lives (Years) Customer relationships: TruSight HLA $ 380 2.6 Acquired in-process technology: AlloSeq HLA 2,719 — Acquired in-process technology: AlloSeq BMT 2,103 — Total $ 5,202

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	6. GOODWILL AND INTANGIBLE ASSETS Goodwill Goodwill is recorded when the purchase price of an acquisition exceeds the fair value of the net tangible and identified intangible assets acquired. The Company reported $12.0 million of goodwill on the condensed consolidated balance sheet as of each of June 30, 2018 and December 31, 2017. Goodwill is tested annually for impairment at the reporting unit level during the fourth quarter or earlier upon the occurrence of certain events or substantive changes in circumstances. On January 1, 2017, the Company adopted ASU 2017-04, which eliminated the Step 2 requirement of the goodwill impairment test. Instead, the goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. The Company determined that the decrease in its market capitalization in the first quarter of 2017 constituted an indicator of impairment and therefore a goodwill impairment test was completed as of March 31, 2017. The goodwill impairment test determined that the fair value of the Pre-Transplant reporting unit was $3.5 million, which was lower than its carrying value. Accordingly, the Company recorded a goodwill impairment charge of $2.0 million as of March 31, 2017, which represented the remaining goodwill balance in the Pre-Transplant reporting unit. The significant assumptions utilized in the March 31, 2017 discounted cash flow analysis for the Pre-Transplant reporting unit were a discount rate of 16.6%, a terminal growth rate of 3.2% and a capitalization multiple of 7.48. There were no indicators of impairment in the three and six months ended June 30, 2018. Intangible Assets The following tables present details of the Company’s intangible assets as of June 30, 2018 (in thousands): June 30, 2018 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Net Amount Remaining Useful (In Intangible assets with finite lives: Customer relationships: Allenex $ 12,650 $ (1,810 ) $ (1,117 ) $ 9,723 12.5 Customer relationships: Conexio 28 (5 ) (1 ) 22 7.6 Customer relationships: TruSight HLA 380 (12 ) — 368 2.5 Developed technology: Olerup SSP 11,650 (2,524 ) (987 ) 8,139 7.5 Acquired technology: Olerup QTYPE 4,510 (528 ) (402 ) 3,580 12.5 Acquired technology: Olerup SBT 127 (21 ) (6 ) 100 7.6 Acquired technology: dd-cfDNA 6,650 (381 ) — 6,269 12.3 Trademarks 2,260 (384 ) (139 ) 1,737 12.5 Total intangible assets with finite lives $ 38,255 $ (5,665 ) $ (2,652 ) $ 29,938 Acquired in-process technology: AlloSeq HLA 2,719 — — 2,719 — Acquired in-process technology: AlloSeq BMT 2,103 — — 2,103 — Total intangible assets $ 43,077 $ (5,665 ) $ (2,652 ) $ 34,760 The following tables present details of the Company’s intangible assets as of December 31, 2017 (in thousands): December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Net Amount Remaining Useful (In Customer relationships: Allenex $ 12,650 $ (1,394 ) $ (250 ) $ 11,006 13.0 Customer relationships: Conexio 28 (3 ) 1 26 8.1 Developed technology: Olerup SSP 11,650 (1,942 ) (258 ) 9,450 8.0 Acquired technology: Olerup QTYPE 4,510 (376 ) (84 ) 4,050 13.0 Acquired technology: Olerup SBT 127 (14 ) 5 118 8.1 Acquired technology: dd-cfDNA 6,650 (127 ) — 6,523 12.9 Trademarks 2,260 (310 ) 16 1,966 13.0 Total intangible assets $ 37,875 $ (4,166 ) $ (570 ) $ 33,139 Amortization expense was $0.6 million and $0.6 million for the three months ended June 30, 2018 and 2017, respectively. For the three months ended June 30, 2018, expenses of $0.4 million and $0.2 million were amortized to cost of product and sales and marketing expense, respectively. For the three months ended June 30, 2017, expenses of $0.4 million and $0.2 million were amortized to cost of product and sales and marketing expense, respectively. Amortization expense was $1.2 million for each of the six months ended June 30, 2018 and 2017. For the six months ended June 30, 2018, expenses of $0.7 million and $0.5 million were amortized to cost of product and sales and marketing, expense, respectively. For the six months ended June 30, 2017, expenses of $0.7 million and $0.5 million were amortized to cost of product and sales and marketing expense, respectively. The following table summarizes the Company’s estimated future amortization expense of intangible assets with finite lives as of June 30, 2018 (in thousands): Years Ending December 31, Cost of Product Sales and Marketing Total Remainder of 2018 $ 949 $ 533 $ 1,482 2019 1,893 1,067 2,960 2020 1,893 1,067 2,960 2021 1,893 920 2,813 2022 1,893 920 2,813 2023 1,893 920 2,813 Thereafter 7,673 6,424 14,097 Total future amortization expense $ 18,087 $ 11,851 $ 29,938 The Company evaluates the carrying value of the intangible assets, not subject to amortization, related to in‑process research and development (“IPR&D”) assets, which are considered to be indefinite‑lived until the completion or abandonment of the associated research and development efforts. Accordingly, amortization of the IPR&D assets will not occur until the products reach commercialization. During the period the assets are considered indefinite‑lived, they are tested for impairment on an annual basis, as well as between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate that the fair values of the IPR&D assets are less than their carrying amounts. An impairment loss would be recorded when the fair value of an IPR&D asset is less than its carrying value. If and when development is complete, which generally occurs when the products are made commercially available, the associated IPR&D asset will be deemed definite‑lived and will then be amortized based on its estimated useful life.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	7. BALANCE SHEET COMPONENTS Inventory Inventory consisted of the following (in thousands): June 30, 2018 December 31, 2017 Finished goods $ 1,379 $ 2,569 Work in progress 1,548 1,471 Raw materials 1,739 1,489 Total inventory $ 4,666 $ 5,529 Accrued and other liabilities Accrued and other liabilities consisted of the following (in thousands): June 30, 2018 December 2017 Clinical studies $ 1,580 $ 1,115 Test sample processing fees 614 633 Shares withheld in lieu of taxes 557 — Deferred rent – current portion 419 419 Professional fees 398 475 Customer overpayments and refunds due 259 270 Capital leases – current portion 139 13 Accrued royalty 159 — Software implementation costs 50 94 Accrued interest payable 37 81 Other accrued expenses 491 635 Total accrued and other liabilities $ 4,703 $ 3,735

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. COMMITMENTS AND CONTINGENCIES Leases The Company leases its operating and office facilities for various terms under long-term, non-cancelable operating lease agreements in Brisbane, California; West Chester, Pennsylvania; Fremantle, Australia; and Stockholm, Sweden. The lease for the Company’s facility in Vienna, Austria is on a month-to-month basis. The facility leases expire at various dates through 2020. In the normal course of business, it is expected that these leases will be renewed or replaced by leases on other properties. Rent expense under the non-cancelable operating leases was $0.4 million for each of the three months ended June 30, 2018 and 2017. Rent expense under the non-cancelable operating leases was $0.9 million for each of the six months ended June 30, 2018 and 2017. Future minimum lease commitments under these operating and capital leases on June 30, 2018, are as follows (in thousands): Years Ending December 31, Capital Leases Operating Leases Remainder of 2018 $ 85 $ 1,111 2019 162 2,133 2020 157 2,046 2021 45 10 2022 — 7 Total future minimum lease payments $ 449 $ 5,307 The current portion of obligations under capital leases is included in accrued and other liabilities on the balance sheets. The long-term portion is included in other liabilities on the balance sheets. Royalty Commitments Roche Molecular Systems, Inc. (“Roche”) In November 2004, the Company entered into a license agreement with Roche pursuant to which Roche granted the Company the right to use certain Roche technology relating to PCR, and quantitative real-time PCR in clinical laboratory services, including in connection with AlloMap. This is a non-exclusive license agreement in the United States covering claims in multiple Roche patents. Under the license agreement, the Company incurred royalty expenses as a percentage of combination services revenue and classifies those expenses as a component of cost of testing in the condensed consolidated statements of operations. Royalty expenses in connection with the Roche agreement were $0.3 million and $0.6 million for the three and six months ended June 30, 2017, respectively. Effective September 30, 2017, no future royalties are payable by the Company under the Roche agreement. The Board of Trustees of the Leland Stanford Junior University (“Stanford”) In June 2014, the Company entered into a license agreement with Stanford, or the Stanford License, which granted the Company an exclusive license to a patent relating to the diagnosis of rejection in organ transplant recipients using dd-cfDNA. Under the terms of the Stanford License, the Company is required to pay an annual license maintenance fee, six milestone payment amounts and royalties in the low single digits of net sales of products incorporating the licensed technology. The license maintenance fee may be offset against earned royalty payments due on net sales in that year. Commercial sales of AlloSure, which incorporates the licensed technology from Stanford, began in October 2017. In each of the three and six months ended June 30, 2018, the Company incurred royalties of $0.2 million to Stanford. Conexio On January 20, 2017, the Company acquired the business assets of Conexio, which included machinery, facilities leases, know-how and the opportunity to retain key Conexio employees to continue producing and selling the SBT line of products. The Company makes quarterly payments to Conexio of 20% of the gross revenue from the sale of the SBT products using the purchased assets up to an aggregate total of $0.7 million. During the three months ended June 30, 2018 and June 30, 2017, the Company paid less than $0.1 million and nil, respectively. During each of the six months ended June 30, 2018 and June 30, 2017, the Company paid less than $0.1 million. Illumina On May 4, 2018, the Company entered into the License Agreement with Illumina. The License Agreement requires the Company to pay royalties in the mid-single to low-double digits on sales of future commercialized products. In the three months ended June 30, 2018, the Company paid no royalties to Illumina. Other Commitments Pursuant to the License Agreement with Illumina, the Company is obligated to complete timely development and commercialization of other NGS product line for use in the Field, and has agreed to minimum purchase commitments of finished products and raw materials from Illumina through 2023. Litigation From time to time, the Company may become involved in litigation and other legal actions. The Company estimates the range of liability related to any pending litigation where the amount and range of loss can be estimated. The Company records its best estimate of a loss when the loss is considered probable. Where a liability is probable and there is a range of estimated loss with no best estimate in the range, the Company records a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability had been incurred at the date of the financial statements and (ii) the range of loss can be reasonably estimated. In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for indemnification for certain liabilities. The exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its directors and executive officers for specified events or occurrences, subject to some limits, while they are serving at the Company’s request in such capacities. There have been no claims to date and the Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company has not recorded any liabilities for these agreements as of June 30, 2018 and as of December 31, 2017.

License and Other Revenue

License and Other Revenue	6 Months Ended
	Jun. 30, 2018
Revenues [Abstract]
License and Other Revenue	9. LICENSE AND OTHER REVENUE Diaxonhit In June 2013, the Company entered into an exclusive Distribution and Licensing Agreement with Diaxonhit, SA (“Diaxonhit”) a French public company, whereby Diaxonhit agreed to have the AlloMap test performed in a European laboratory and commercialize the test in the European Economic Area (“EEA”). The agreement will expire at the later of the last-to-expire patent in the EEA or ten years from the first commercial sale of the test in the EEA, which occurred in 2014. Consideration under the agreement included an upfront cash payment of approximately €387,500 ($408,000) that is designated to offset royalties earned by the Company. The Company is entitled to receive royalties from Diaxonhit as a percentage of net sales, as defined in the agreement, of AlloMap tests in the mid to high teens. Upon confirmation that the CE mark was in place, the Company also received an equity payment of Diaxonhit common stock with a value of €387,500 ($476,000). The Company sold the shares of common stock in July 2013 for total consideration of $467,000. The CE mark is a mandatory conformity marking for certain products sold within the EEA. Other performance obligations for which the Company may recognize revenue includes agreed-upon per unit pricing for the supply of AlloMap products, and additional royalties that are payable upon the achievement of various sales milestones by Diaxonhit. Commercial sales of the AlloMap test began in the EEA in June 2014. Total revenues and royalties recognized from this arrangement for each of the three months ended June 30, 2018 and 2017 were $10,000. Total revenue and royalties recognized from this arrangement for each of the six months ended June 30, 2018 and 2017 were $19,000. CardioDx, Inc. In 2005, the Company entered into a services agreement with what at the time was a related party, CardioDx, Inc. (“CDX”), whereby the Company provided CDX with biological samples and related data and performed laboratory services on behalf of CDX. Each company granted the other a worldwide license to certain of its intellectual property rights. Pursuant to this agreement, CDX pays royalties to the Company in an amount equal to a low single-digit percentage of the cash collected from sales of CDX licensed products. The royalty obligation to the Company continues until 2019. The Company recognizes royalty revenues when payments are received as it was assessed that collection was not able to be estimated. Royalty revenues for each of the three months ended June 30, 2018 and 2017 were $0.2 million. Royalty revenues for the six months ended June 30, 2018 and 2017 were $0.3 million and $0.2 million, respectively. Royalty revenues are included in license revenue on the condensed consolidated statements of operations. The Company had no receivable balance from CDX as of June 30, 2018 and December 31, 2017.

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Transfers And Servicing [Abstract]
Debt	10. DEBT Debt consisted of the following (in thousands): June 30, 2018 December JGB Debt $ — $ 7,743 Danske Bank Credit Facility — 6,763 SSP Primers Loan — 1,215 Current portion of long-term debt $ — $ 15,721 Perceptive Credit Agreement $ 13,337 $ — JGB Debt — 14,168 Danske Bank Term Loan — — FastPartner Subordinated Promissory Notes — 2,400 Al Amoudi Subordinated Promissory Notes — 1,770 Long-term debt, net of current portion $ 13,337 $ 18,338 Unamortized debt discount and issuance costs as of June 30, 2018 and December 31, 2017 were $1.7 million and $4.6 million, respectively. Total interest accrued on debt as of June 30, 2018 and December 31, 2017 was nil and $0.3 million, respectively. The current accrued interest balance of $0.1 million and long-term accrued interest balance of $0.2 million as of December 31, 2017, were recorded in accrued and other liabilities and in other liabilities long-term, respectively, in the condensed consolidated balance sheets. As of June 30, 2018, future debt maturities were as follows (in thousands): Years Ending December 31, Amount 2021 $ 2,025 2022 2,700 2023 10,275 Total debt maturities 15,000 Less: debt discount and issuance costs (1,663 ) Long-term debt, net carrying value 13,337 Perceptive Credit Agreement On April 17, 2018, the Company entered into a credit agreement with Perceptive for an initial term loan of $15.0 million (“Tranche A Term Loan”) with a second tranche of $10.0 million available at the Company’s option, subject to the satisfaction of customary conditions (the “Tranche B Term Loan” and, together with the “Tranche A Term Loan”, the “Term Loam”). Approximately $11.1 million of the proceeds of the Tranche A Term Loan were used to fully repay the Company’s outstanding indebtedness, including accrued interest, with FastPartner AB, Mohammed Al Amoudi and Danske on April 17, 2018 In connection with the Perceptive Credit Agreement, the Company entered into a Security Agreement with Perceptive, as administrative agent. The Security Agreement provides that the Term Loan is secured by substantially all of the Company’s assets and a pledge of 65% of the equity interests of CareDx International AB. The Term Loan accrues interest per annum at 9.00% (the “Applicable Margin”) plus the greater of the one-month LIBOR or 1.5%. Payments under the Perceptive Credit Agreement are interest-only until the first principal payment is due on April 30, 2021, followed by monthly payments of principal and interest through the scheduled maturity date on April 17, 2023. The Term Loan may be prepaid by the Company, in whole or in part at any time, subject to a prepayment fee. The Company paid a fee of $0.3 million to Perceptive in its capacity as the administrative agent under the Security Agreement. In addition, on April 17, 2018, the Company issued to Perceptive the Perceptive Tranche A Warrant to purchase up to 140,000 shares of common stock of the Company at an initial exercise price of $8.60. The Perceptive Tranche A Warrant will be exercisable commencing on October 17, 2018 and will terminate, if not earlier exercised, on April 17, 2025. The Tranche B Term Loan is available at the Company’s option at any time from April 17, 2018 to April 17, 2019, subject to the Company achieving certain product revenue targets and satisfying customary conditions. In the event the Company exercises its option for the Tranche B Term Loan, the Company will pay to Perceptive as the administrative agent out of the proceeds of the Tranche B Term Loan a fee in the amount equal to 1.75% of the principal amount of the Tranche B Term Loan advanced on such date. If the Tranche B Term Loan is funded, the Company will issue to Perceptive an additional warrant (the “Tranche B Warrant”), to purchase up to 93,333 shares of common stock at an initial exercise price of $8.60 and with other terms consistent with the Tranche A Warrant. The Perceptive Credit Agreement contains financial covenants related to minimum cash balance and trailing twelve month revenue. As of June 30, 2018, the Company was in compliance with the financial covenants. The Perceptive Credit Agreement provides for customary events of default, including, among other things, nonpayments of principal, interest and other amounts, inaccuracies in representations and warranties, failure to comply with covenants, defaults on other material indebtedness, bankruptcy or insolvency, judgments, changes of control or impairments of Perceptive’s security interests. Upon the occurrence of an event of default and following any applicable cure periods, if any, the Applicable Margin shall automatically increase 3.00% per annum (the “Default Rate”). This Default Rate may be applied to the outstanding loan balances, and the Agent may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Perceptive Credit Agreement . The Company concluded that the early repayment provisions were an embedded derivative liability requiring bifurcation. The following table summarizes the Company’s carrying value of the Perceptive Security Agreement (in thousands) on April 17, 2018, the issuance date (in thousands): April 17, 2018 Debt principal $ 15,000 Less: Issuance cost (669 ) Discount related to issued warrants (784 ) Embedded derivative liability (245 ) Total debt discount (1,698 ) Carrying value $ 13,302 JGB Debt On March 15, 2017, the Company entered into a Securities Purchase Agreement (the “Securities Purchase Agreement”) with JGB pursuant to which the Company issued to JGB debentures (the “Debentures”) with an aggregate principal amount of $27.8 million and warrants to purchase shares of the Company’s common stock (the “JGB Warrants”) for net proceeds of $24.0 million (the “Financing”). The Company used $11.2 million of the net proceeds from the Financing to repay its existing indebtedness under the Loan Agreement with East West Bank and was required to maintain restricted cash of $9.4 million. Under the Securities Purchase Agreement, the Debentures would have matured on February 28, 2020, accrued interest at 9.5% per year and were convertible into an aggregate of approximately 6,092,105 shares of the Company’s common stock at a price of $4.56 per share (the “Conversion Price”), subject to adjustment for accrued and unpaid interest and upon the occurrence of certain transactions, at the holder’s option. Additionally, after September 1, 2017, upon the satisfaction of certain conditions, including the volume weighted average price of the Company’s common stock exceeding 250% of the Conversion Price for twenty consecutive trading days, the Company could have required that the Debentures be converted into shares of the Company’s common stock, subject to certain limitations. Commencing on March 1, 2018, each of the holders of the Debentures had the right, at its option, to require the Company to redeem up to $937,500 of the outstanding principal amount of its Debenture per month. The Company was required to promptly, but in any event no more than one trading day after the holder delivers a redemption notice to the Company, pay the applicable redemption amount in cash or, at the Company’s election and subject to certain conditions, in shares of the Company’s common stock. If the Company elected to pay the redemption amount in shares of the Company’s common stock, then the shares would have been delivered based on a price equal to the lowest of (a) 88% of the average of the three lowest volume weighted average prices of the Company’s common stock over the prior 20 trading days, (b) 88% of the prior trading day’s volume weighted average price, or (c) the Conversion Price. After either a change of control transaction, as defined in the Debentures, or February 28, 2018, subject to the satisfaction of certain conditions, the Company could have redeemed all of the then outstanding principal amount of the Debentures for cash by paying the outstanding principal balance, accrued and unpaid interest, and a payment premium. The payment premium would have been calculated by multiplying the outstanding balance and the following percentage: (i) 15% if the Debentures were prepaid on or prior to March 1, 2018, (ii) 8% if the Debentures were prepaid after March 1, 2018 but prior to March 1, 2019, and (iii) 5% if the Debentures were prepaid on or after March 1, 2019. The Company’s obligations under the Debentures could have been accelerated upon the occurrence of certain events of default as specified in the agreement. In the event of default and acceleration of the Company’s obligations, the Company would have been required to pay (i) 115% of all amounts of principal and interest then outstanding under the Debentures in cash if the Debentures were accelerated prior to March 1, 2018, (ii) 108% of all amounts of principal and interest then outstanding under the Debentures in cash if the Debentures were accelerated after March 1, 2018, but prior to March 1, 2019, and (iii) 105% of all amounts of principal and interest then outstanding under the Debentures in cash if the Debentures were accelerated after March 1, 2019. The Company’s obligations under the Debentures were secured under a Security Agreement by a senior lien on all of the Company’s assets, other than its interest in CareDx International AB (formerly known as Allenex AB), which was subject to a negative pledge prohibiting the incurrence of additional or replacement debt. The Debentures contained customary affirmative and restrictive covenants and representations and warranties, including financial reporting obligations, a restriction on the Company’s ability to pay cash dividends on its common stock and limitations on indebtedness, liens, investments, distributions, transfers, corporate changes, deposit accounts and subsidiaries. The Company was also required to maintain a minimum cash amount at all times, achieve commercialization of AlloSure by a certain date and achieve certain gross profit targets for sales of its AlloMap product. In connection with the Financing, on March 15, 2017, the Company and the Purchasers entered into a Registration Rights Agreement (the “Registration Rights Agreement”) pursuant to which, among other things, the Company agreed to prepare and file one or more registration statements with the SEC for the purpose of registering for resale any shares of Common Stock that may be issued by the Company upon the conversion or redemption of the Debentures or the exercise of the JGB Warrants. The Debentures included certain embedded derivatives that required bifurcation, including settlement and penalty provisions. The compound embedded derivatives were remeasured at each reporting period and the change in fair value was recognized in the consolidated statements of operations. See also Note 4, “Fair Value Measurements”. The following table summarizes the Company’s carrying value of the JGB Debt (in thousands) on the March 15, 2017 issuance date: March 15, 2017 Debt principal $ 27,780 Less: Issuance cost (998 ) Original issue discount (2,780 ) Original warrant valuation (900 ) Embedded Derivative Liability (2,290 ) Total debt discount (6,968 ) Carrying value $ 20,812 As a result of the issuance of 1,022,544 shares of the Company’s common stock issued at a price per share equal to $1.12 pursuant to the amendments to the Conditional Share Purchase Agreements, the conversion price of the Debentures decreased from $4.56 per share to $4.40 per share, effective July 3, 2017. As a result of the 2017 Public Offering in accordance with the anti-dilution provisions in the Debentures, effective October 5, 2017, the conversion price of the Debentures decreased from $4.40 to $4.34 per share. On October 5, 2017, JGB elected to convert $1.25 million of outstanding principal under the Debentures into shares of common stock. Accordingly, the Company issued 288,022 shares of common stock to JGB at a price per share of $4.34. As a result of the sale of the 651,240 shares of common stock pursuant to the underwriters’ full exercise of their option to purchase additional shares in accordance with the anti-dilution provisions in the Debentures, effective October 10, 2017, the conversion price of the Debentures were decreased from $4.34 per share to $4.33 per share. As of December 31, 2017, the JGB Debt had an outstanding principal balance of $26.5 million. On March 1, 2018, the Company notified JGB of its intent to prepay on April 13, 2018 in full the outstanding principal and interest under the Debentures. Pursuant to the terms of the Debentures, on April 13, 2018, the Company would have been obligated to pay the full amount of the outstanding principal balance of the Debentures, plus accrued and unpaid interest thereon and a prepayment premium equal to 8% of the outstanding principal balance in cash. In February and March 31, 2018, JGB converted the remaining $26.7 million of principal and accrued interest of the JGB Debt into an aggregate of 6,161,331 shares of the Company’s common stock. In connection with these conversions in the three months ended March 31, 2018, the Company recognized $6,000 to common stock and $38.8 million to additional paid in capital; the unamortized debt discount of $2.7 million was extinguished; and the compound derivative liability of $12.1 million was also extinguished. The JGB Debt conversion resulted in a $2.8 million loss on debt extinguishment that was included in other expense, net in the condensed consolidated statements of operations. Danske Bank Term Loan and Credit Facility On June 25, 2013, Allenex entered into a term loan facility (the “Term Loan Facility”) with Danske in an aggregate principal amount of up to SEK 71,000,000 (approximately $8.8 million). The Term Loan Facility was available for utilization in advances of a minimum of SEK 5,000,000 (approximately $0.6 million) and if more, integral multiples of SEK 1,000,000 (approximately $0.1 million). The interest rate applicable to each advance was the percentage rate per annum calculated as the aggregate of (i) Stockholm Interbank Offered Rate (“STIBOR”) (as defined in the Term Loan Facility) and (ii) the Margin (as described in the Term Loan Facility) at 3% conditional on the fulfillment of certain criteria. In March 2015, Allenex entered into a first amendment to the Term Loan Facility, pursuant to which additional loans were granted. In August 2015, Allenex entered into a second amendment to the Term Loan Facility, pursuant to which the term of the Term Loan Facility was extended. In December 2015, Allenex entered into a waiver and amendment agreement relating to the Term Loan Facility, pursuant to which the change of control provision was waived and amended. In March 2016, Allenex entered into another amendment to the Term Loan Facility, which modified the repayment schedule for advances under the Term Loan Facility. Under this Term Loan Facility, SEK 47,000,000 (approximately $5.6 million) was outstanding as of March 31, 2018 and was due on June 30, 2018. This was classified as a current debt as of March 31, 2018. On June 18, 2015, Allenex also entered into a short term credit facility (“Credit Facility”) with Danske with total available credit of SEK 8,000,000 (approximately $1.0 million). As of August 4, 2016, the available credit under the Credit Facility with Danske was increased to SEK 10,000,000 (approximately $1.2 million). As of March 31, 2018, the total outstanding balance due to Danske under the Credit Facility was approximately SEK 3,850,000 (approximately $0.5 million), and was due on June 30, 2018. A quarterly debt covenant in the Term Loan Facility with Danske was violated on March 31, 2017, June 30, 2017, and September 30, 2017. The Company obtained a waiver for these violations. The waiver was conditional upon, among other things, the Company making a principal repayment of SEK 6,000,000 (approximately $0.7 million) by October 31, 2017. This amount was paid on October 31, 2017. The Company was not in compliance with certain debt covenants as of December 31, 2017 or March 31, 2018. The Company repaid the full outstanding amount of SEK 47,000,000 (approximately $5.6 million), including accrued interest of SEK 142,000 (approximately $17,000), under the Danske Term Loan and Credit Facility on April 17, 2018. FastPartner Subordinated Promissory Notes On June 28, 2013, Allenex issued a SEK 9,400,000 (approximately $1.1 million) subordinated promissory note to FastPartner, which had an interest rate of 10.00%. On December 29, 2015, Allenex issued a SEK 2,000,000 (approximately $0.2 million) subordinated promissory note to FastPartner, which had an annual interest rate of 10.00%. On March 7, 2016, Allenex issued a SEK 4,000,000 (approximately $0.5 million) subordinated promissory note to FastPartner, which had an annual interest rate of 10.00%. Pursuant to an intercreditor agreement, until the Term Loan Facility with Danske is repaid, FastPartner may not demand or receive payment of its subordinated promissory note, or foreclose on any collateral securing Allenex’s obligations under the subordinated promissory note, without Danske’s prior written consent. Allenex’s obligations under the promissory note are secured by a pledge of Allenex shares to FastPartner. The full amount of the subordinated promissory note was due July 1, 2017. On July 1, 2017, the Company entered into a note agreement with FastPartner (the “FastPartner Note Agreement”) pursuant to which, among other things, Allenex and FastPartner agreed that all amounts owed under the above subordinated promissory notes would be governed by the FastPartner Note Agreement and to defer repayment of the principal outstanding amount of SEK 15,400,000 (approximately $1.9 million) plus accrued interest of $0.5 million until March 31, 2019. I nterest began accruing on such amount at a rate of 10% per annum, and in the event the Company makes any cash amortization repayments to JGB of the JGB Debt, or any replacement debt, Allenex will repay in cash a portion of the amount outstanding under the FastPartner Note Agreement equal to 8% of any such cash amortization repayment. As of each of March 31, 2018 and December 31, 2017, the principal outstanding amount remained at SEK 19,757,000 (approximately $2.4 million). The Company repaid the full amount outstanding of SEK 21,300,000 (approximately $2.5 million), including accrued interest of SEK 1,600,000 (approximately $0.2 million), under the FastPartner Note Agreement on April 17, 2018. Mohammed Al Amoudi Subordinated Promissory Note On June 28, 2013, Allenex issued a SEK 10,600,000 (approximately $1.2 million) subordinated promissory note to Mohammed Al Amoudi, which provides for an annual interest rate of 10.00%. Pursuant to an intercreditor agreement, until the Term Loan Facility with Danske is repaid, Mohammed Al Amoudi may not demand or receive payment of his subordinated promissory note, or foreclose on any collateral securing Allenex’s obligations under the subordinated promissory note, without Danske’s prior written consent. Allenex’s obligations under the promissory note are secured by a pledge of Allenex shares to Mohammed Al Amoudi. The full amount of the subordinated promissory note was due July 1, 2017. On July 1, 2017, the Company entered into a note agreement with Mohammed Al Amoudi (the “Al Amoudi Note Agreement”) pursuant to which, among other things, Allenex and Mohammed Al Amoudi agreed to defer repayment of the principal outstanding amount of SEK 10,600,000 (approximately $1.3 million) plus accrued interest of $0.5 million until March 31, 2019. nterest began accruing on such amount at a rate of 10% per annum, and in the event the Company makes any cash amortization repayments to JGB of the JGB Debt, or any replacement debt, Allenex will repay in cash a portion of the amount outstanding under the Al Amoudi Note Agreement equal to 6% of any such cash amortization repayment. As of each of March 31, 2018 and December 31, 2017, the principal outstanding amount remained at SEK 14,575,000 (approximately $1.7 million). The Company repaid the full amount outstanding of SEK 15,700,000 (approximately $1.9 million), including accrued interest of SEK 1,200,000 (approximately $0.1 million) under the Al Amoudi Note Agreement on April 17, 2018. Loan Agreement with SSP Primers Aktieboulag On February 25, 2015, Allenex entered into a SEK 14,000,000 (approximately $1.7 million) loan agreement with SSP Primers Aktieboulag, pursuant to which SEK 4,000,000 (approximately $0.5 million) was paid on March 7, 2016. The loan amount outstanding as of December 31, 2017 was SEK 10,000,000 (approximately $1.2 million) plus accrued interest of SEK 650,000 (approximately $0.1 million) and was fully paid on February 26, 2018.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
Stockholders Equity Note [Abstract]
Stockholders' Equity	11. STOCKHOLDERS’ EQUITY 2017 Public Offering On October 10, 2017, the Company sold in the 2017 Public Offering an aggregate of 4,992,840 shares of its common stock, including 651,240 shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares to cover over-allotments, at a public offering price of $4.00 per share. Net proceeds from the 2017 Public Offering were $18.3 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. JGB Debt On October 5, 2017, JGB converted $1.25 million of outstanding principal under the Debentures into shares of common stock. Accordingly, the Company issued 288,022 shares of common stock to JGB at a price per share of $4.34. In the three months ended March 31, 2018, JGB converted the remaining $26.7 million of outstanding principal and accrued interest for a total issuance of 6,161,331 shares of the Company’s common stock at a price per share of $4.33. Contingent Consideration Liability The Company had a contingent obligation to issue 227,845 shares of the Company’s common stock to the former owners of ImmuMetrix, Inc .

401(K) Plan

401(K) Plan	6 Months Ended
	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
401(K) Plan	12. 401(K) PLAN The Company sponsors a 401(k) defined contribution plan covering all U.S. employees under the Internal Revenue Code. Employee contributions are voluntary and are determined on an individual basis subject to the maximum allowable under federal tax regulations. On January 1, 2018, the Company began to make contributions to the employee plan. For each of the three and six months ended June 30, 2018, the Company incurred an expense of $0.1 million related to contributions into the plan.

Warrants

Warrants	6 Months Ended
	Jun. 30, 2018
Warrants [Abstract]
Warrants	13. WARRANTS The Company issues common stock warrants in connection with debt or equity financings to a lender, a placement agent or an investor. Issued warrants are considered standalone financial instruments and the terms of each warrant are analyzed for equity or liability classification in accordance with US GAAP. Warrants that are classified as liabilities usually have various features that would require net-cash settlement by the Company. Warrants that are not liabilities, derivatives and/or meet exception criteria are classified as equity. Warrants liabilities are re-measured at fair value at each period end with changes in fair value recorded in the condensed statements of operations until expired or exercised. The Company utilizes the Monte Carlo Simulation Model to estimate the fair value of its warrants. Refer to Note 4 for further details. Warrants that are classified as equity are valued at fair value on the date of issuance, recorded in additional paid in capital and not re-measured. On January 1, 2018, the Company adopted new accounting guidance (refer to Note 2) and reclassified the warrants to purchase 1,338,326 shares of common stock issued to JGB from liability to equity at the fair value of $6.6 million. In the three months ended June 30, 2018, warrants to purchase 445,000 shares of common stock were exercised for a cash payment of $0.5 million. In the six months ended June 30, 2018, warrants to purchase 468,000 shares of common stock were exercised for a cash payment of $0.5 million. The warrant liability was re-measured prior to the exercise and a change in fair value of $5.2 million and $5.4 million was recorded in the condensed consolidated statement of operations for the three and six months ended June 30, 2018, respectively. As of June 30, 2018, outstanding warrants to purchase common stock were: Classified as Original Term Exercise Price Number of Shares Underlying Warrants Original issue date: August 2009 Equity 10 years $ 21.78 33,473 July 2010 Equity 9 years $ 21.78 6,694 August 2012 Equity 7 years $ 21.78 167,182 January 2015 Equity 5 years $ 6.96 34,483 April 2016 (a) Liability 7 years $ 1.12 469,124 April 2016 (b) Liability 5 years $ 1.12 136,300 June 2016 (c) Liability 7 years $ 4.00 1,002,507 March 2017 (d) Equity 5 years $ 4.67 1,338,326 April 2018 (e) Equity 7 years $ 8.60 140,000 April 2018 (f) Equity 7 years $ 8.60 93,333 3,421,422 (a) Issued on April 14, 2016 in connection with the private placement to certain accredited investors. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with such private placement was adjusted from $4.98 to $4.00, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $4.00 to $1.12, effective July 3, 2017. (b) Issued on April 14, 2016 in connection with the private placement to placement agents. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $3.99 to $1.12, effective July 3, 2017. (c) Issued on June 15, 2016 in connection with a subsequent private placement. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with the subsequent private placement was adjusted from $4.98 per share to $4.00 per share, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. The exercise price remained at $4.00 as the anti-dilution provision was waived for the issuance of shares related to the July 3, 2017 amendment to the Conditional Share Purchase Agreements. (d) Issued on March 15, 2017 in connection with the JGB Debt. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the number of shares issuable pursuant to the JGB Warrants increased from 1,250,000 to 1,296,679 and the exercise price of the JGB Warrants was adjusted from $5.00 to $4.82, effective July 3, 2017. As a result of the 2017 Public Offering, effective October 5, 2017, the aggregate number of shares of common stock issuable upon exercise of the JGB Warrants increased from 1,296,679 to 1,338,326 shares and the exercise price of the JGB Warrants decreased from $4.82 to $4.67 per share. (e) Issued on April 17, 2018 in connection with the Perceptive Credit Agreement. (f) The Perceptive Credit Agreement included a Tranche B loan amount

Stock Incentive Plans

Stock Incentive Plans	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	14. STOCK INCENTIVE PLANS Stock Options and Restricted Stock Units (“RSU”) The following table summarizes option and unvested RSU activity under the Company’s 2014 Equity Incentive Plan and 2016 Inducement Plan and related information: Shares Available for Grant Stock Options Outstanding Weighted- Average Exercise Price Number of RSU Shares Weighted- Average Grant Date Fair Value Balance—December 31, 2017 156,429 1,941,473 $ 4.21 439,926 $ 4.39 Additional options authorized 1,957,075 — — — — Restricted stock grants (17,919 ) — — — — RSUs granted (714,834 ) — — 714,834 11.63 RSUs forfeited 13,050 — — (13,050 ) 4.87 RSUs vested — — — (244,806 ) 9.30 Repurchases of common stock under employee incentive plans 67,656 Options granted (809,634 ) 809,634 11.05 — — Options exercised — (167,379 ) 1.07 — — Options forfeited 20,453 (20,453 ) 4.78 — — Options expired 1,817 (1,817 ) 3.55 — — Balance—June 30, 2018 674,093 2,561,458 $ 6.57 896,904 $ 8.83 The total intrinsic value of options exercised was $0.9 million in the six months ended June 30, 2018. As of June 30, 2018, the total intrinsic value of outstanding RSUs was approximately $3.0 million and there were $6.6 million of unrecognized compensation costs related to RSUs, which are expected to be recognized over a weighted-average period of 3.37 years. As of June 30, 2018, the total intrinsic value of outstanding options was approximately $13.6 million and there were $5.8 million of unrecognized compensation costs related to options, which are expected to be recognized over a weighted-average period of 3.33 years. Options outstanding that have vested and are expected to vest at June 30, 2018 are as follows: Number of Shares Weighted Exercise Price Weighted Aggregate Intrinsic (In Vested 991,627 $ 6.57 6.73 $ 7,400 Expected to vest 1,360,609 7.83 7.54 6,191 Total 2,352,236 $ 13,591 2014 Employee Stock Purchase Plan During the offering period in 2017 that ended on December 31, 2017, 34,176 shares were purchased for aggregate proceeds of $0.1 million from the issuance of shares, which occurred on January 4, 2018. During the offering period in 2018 that ended on June 30, 2018, 42,534 shares were purchased for aggregate proceeds of $0.3 million from the issuance of shares, which occurred on July 2, 2018. Valuation Assumptions The estimated fair values of employee stock options and ESPP shares were estimated using the Black-Scholes option-pricing model based on the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Employee stock options Expected term (in years) 6.0 6.0 6.0 6.0 Expected volatility 66.00 % 55.46-57.71% 68.75 % 53.07%-57.71% Risk-free interest rate 2.76 % 1.90-1.96% 2.71 % 1.90%-2.12% Expected dividend yield — % — % — % — % Employee stock purchase plan Expected term (in years) 0.5 0.5 0.5 0.5 Expected volatility 105.32 % 62.27 % 105.32 % 62.27 % Risk-free interest rate 1.61 % 0.65 % 1.61 % 0.65 % Expected dividend yield — % — % — % — % Risk-free Interest Rate : Volatility: The Company used an average historical stock price volatility of its own stock and those comparable public companies that were deemed to be representative of future stock price trends. Expected Term: The expected term represents the period for which the Company’s stock-based compensation awards are expected to be outstanding and is based on analyzing the vesting and contractual terms of the awards and the holders’ historical exercise patterns and termination behavior. Expected Dividends: The Company has not paid and does not anticipate paying any dividends in the near future. Stock-based Compensation Expense The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs and ESPP shares for the three and six months ended June 30, 2018 and 2017, included in the statements of operations as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of testing $ 191 $ 63 $ 252 $ 119 Research and development 462 111 675 175 Sales and marketing 466 57 529 95 General and administrative 1,393 264 1,761 497 Total $ 2,512 $ 495 $ 3,217 $ 886 No tax benefit was recognized related to share-based compensation expense since the Company has never reported taxable income and has established a full valuation allowance to offset all of the potential tax benefits associated with its deferred tax assets. In addition, no amounts of stock-based compensation expense were capitalized for the periods presented.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	15. INCOME TAXES The Company’s effective tax rate may vary from the U.S. federal statutory tax rate due to the change in the mix of earnings in tax jurisdictions with different statutory rates, benefits related to tax credits, and the tax impact of non-deductible expenses and other permanent differences between income before income taxes and taxable income. For each of the three months ended June 30, 2018 and 2017, the Company recorded an income tax benefit of $0.4 million. For the six months ended June 30, 2018 and 2017, the Company recorded an income tax benefit of $0.8 million and $0.7 million, respectively. The income tax benefit of $0.4 million and $0.8 million for the three and six months ended June 30, 2018, respectively, is primarily attributable to the recognition of deferred tax assets from foreign losses. The Company assesses the realizability of its net deferred tax assets by evaluating all available evidence, both positive and negative, including (i) cumulative results of operations in recent years, (ii) sources of recent losses, (iii) estimates of future taxable income and (iv) the length of net operating loss carryforward periods. The Company believes that based on the history of its U.S. losses and other factors, the weight of available evidence indicates that it is more likely than not that it will not be able to realize its U.S. net deferred tax assets. Accordingly, the U.S. net deferred tax assets have been offset by a full valuation allowance. In accordance with the SEC’s Staff Accounting Bulletin No. 118 (“SAB 118”), the effects of the Tax Act may be adjusted within a one-year measurement period from the enactment date for items that were previously reported as provisional, or where a provisional estimate could not be made. Income tax provision for the three and six months ended June 30, 2018, did not reflect any adjustment to the previously assessed Tax Act enactment effect. The Company will continue to assess forthcoming guidance and accounting interpretations on the effects of the Tax Act and expects to complete its analysis within the measurement period in accordance with the SEC guidance. Starting in 2018, companies may be subject to global intangible low tax income (“GILTI”), which is a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations as well as the new base erosion anti-abuse tax (“BEAT”) under the Tax Act. GILTI will be effectively taxed at a tax rate of 10.5%. Due to the complexity of the GILTI tax rules, companies are allowed to make an accounting policy choice of either (1) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred or (2) factoring such amounts into a company’s measurement of its deferred taxes under SAB 118. The Company has not yet made an election with respect to GILTI and does not believe GILTI will have an impact on the Company’s 2018 taxes. The Company will continue to review the GILTI and BEAT rules to determine their applicability to the Company as the rules become effective.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	16. SEGMENT REPORTING Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the Chief Operating Decision Maker (“CODM”), or decision making group, whose function is to allocate resources to and assess the performance of the operating segments. The Company has identified its chief executive officer as the CODM. In determining its reportable segments, the Company considered the markets and types of customers served and the products or services provided in those markets. The Company has identified the following two reportable segments, which are the same as its operating segments: • Post-Transplant: This segment focuses on discovery, development and commercialization of clinically differentiated, high-value diagnostic solutions for transplant patients. In post-transplant diagnostics, the Company offers AlloMap, which is a heart transplant molecular test and AlloSure, which is a donor-derived cell free DNA (“dd-cfDNA”) test initially used for kidney transplant patients. • Pre-Transplant: This segment develops, manufactures, markets and sells high quality products that increase the chance of successful transplants by facilitating a better match between a donor and a recipient of stem cells and organs. The pre-transplant product lines include Olerup branded products SSP, SBT, QTYPE and TruSight HLA. There were no intersegment sales for the three and six months ended June 30, 2018 or 2017. The following table summarizes the operating results of the Company’s reportable segments (in thousands): Three Six Months Ended June 30, 2018 2017 2018 2017 Total Segments Revenues $ 17,823 $ 12,046 $ 31,876 $ 23,630 Operating loss (5,209 ) (3,599 ) (10,444 ) (12,143 ) Depreciation and amortization 986 887 2,025 1,821 Post-Transplant Revenues $ 14,171 $ 8,670 $ 24,917 $ 16,587 Operating loss (3,138 ) (2,662 ) (6,333 ) (8,121 ) Depreciation and amortization 316 236 645 498 Pre-Transplant Revenues $ 3,652 $ 3,376 $ 6,959 $ 7,043 Operating loss (2,071 ) (937 ) (4,111 ) (4,022 ) Depreciation and amortization 670 651 1,380 1,323 June 30, December Assets: Post-Transplant $ 48,851 $ 48,734 Pre-Transplant 31,028 34,831 Total assets $ 79,879 $ 83,565 Revenues by geographic regions are based upon the customers’ ship-to address for pre-transplant product revenues and the region of testing for post-transplant service revenue. The following table summarizes reportable revenues by geographic regions (in thousands): Three Three Post-Transplant Pre-Transplant Post-Transplant Pre-Transplant Revenues: North America $ 14,147 $ 1,489 $ 8,647 $ 983 Europe 24 1,856 23 1,863 Australia — 31 — 125 Rest of the World — 276 — 405 Total $ 14,171 $ 3,652 $ 8,670 $ 3,376 Six Six Post-Transplant Pre-Transplant Post-Transplant Pre-Transplant Revenues: North America $ 24,876 $ 2,418 $ 16,549 $ 1,983 Europe 41 3,829 38 3,922 Australia — 105 — 241 Rest of the World — 607 — 897 Total $ 24,917 $ 6,959 $ 16,587 $ 7,043 The following table summarizes long-lived assets, consisting of property and equipment, net, by geographic regions (in thousands): June 30, 2018 December Long-lived assets: North America $ 1,572 $ 1,206 Europe 708 776 Australia 80 93 Total $ 2,360 $ 2,075

Organization and Description 24

Organization and Description of Business (Policies)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Liquidity And Going Concern	Liquidity and Going Concern The Company has incurred significant losses and negative cash flows from operations since its inception and had an accumulated deficit of $288.1 million at June 30, 2018. As of June 30, 2018, the Company had cash and cash equivalents of $16.2 million, and $13.3 million On April 17, 2018, the Company entered into a credit agreement with Perceptive Credit Holdings II, LP (“Perceptive ”) The Company may req uire additional financing in the future to fund working capital and pay its obligations as they come due. Additional financing might include issuance of equity securities, debt, cash from collaboration agreements or a combination of these. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”), and follow the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments that are necessary for a fair statement of the Company’s financial information. The condensed consolidated balance sheet as of December 31, 2017 has been derived from audited financial statements as of that date but does not include all of the financial information required by U.S. GAAP for complete financial statements. Operating results for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany transactions have been eliminated. The Company acquired CareDx International AB, formerly Allenex AB “Allenex”, on April 14, 2016. Since the acquisition of Allenex through March 15, 2018, the Company owned less than 100% of the shares of Allenex and recorded a net loss attributable to noncontrolling interest in its condensed consolidated statements of operations equal to the percentage of the economic or ownership interest retained by the respective noncontrolling parties in such entities. On March 15, 2018, the Company acquired the remaining noncontrolling interest in Allenex and has not reported any noncontrolling interest balances since this date.
Use of Estimates	Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the unaudited condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to (i) variable transaction price consideration related to contracts with customers, (ii) the determination of the accruals for clinical studies, (iii) the fair value of assets and liabilities acquired in business combinations, including contingent consideration, (iv) inventory valuation, (v) the valuation of common stock warrant liability, (vi) the fair value of embedded derivatives, (vii) measurement of stock-based compensation expense, (viii) the determination of the valuation allowance and estimated tax benefit associated with deferred tax assets and net deferred tax liability, (ix) any impairment of long-lived assets, including in-process technology and goodwill, and (x) legal contingencies. Actual results could differ from those estimates.
Concentrations of Credit Risk and Other Risks and Uncertainties	Concentrations of Credit Risk and Other Risks and Uncertainties For the six months ended June 30, 2018 and 2017, approximately 45% and 28%, respectively, of total revenue was derived from Medicare. No other payers or customers represented more than 10% of total revenue for these periods. At June 30, 2018 and December 31, 2017, approximately 24% and 16%, respectively, of accounts receivable was due from Medicare. No other payer or customer represented more than 10% of accounts receivable on either June 30, 2018 or December 31, 2017.
Restricted Cash	Restricted Cash A restricted cash balance of $9.4 million was released upon the full conversion of the debt obligation to JGB Collateral LLC and certain of its affiliates (“JGB”) (refer to Note 10) during the three months ended March 31, 2018 and is no longer classified as restricted cash. As a condition of the lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements and a surety bond. These agreements are collateralized by cash. The cash used to support these arrangements is classified as long-term restricted cash on the accompanying condensed consolidated balance sheets.
Common Stock Warrant Liability and Derivative Liability	Common Stock Warrant Liability and Derivative Liability Common Stock Warrant Liability On January 1, 2018, the Company adopted Accounting Standard Update (“ASU”) No. 2017-11, Accounting for Certain Financial Instruments with Down Round Features and Replacement of the Indefinite Deferral of Mandatorily Redeemable Financial Instruments of Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. Derivative Liability The convertible debt financing with JGB (the “JGB Debt”), included certain embedded derivatives that required bifurcation, including settlement and penalty provisions. The combined embedded derivative was remeasured at each reporting period with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations. As of March 27, 2018, the JGB Debt was fully converted to shares of the Company’s common stock. The change in the fair market value of the derivative liability through March 27, 2018 was recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations. On April 17, 2018, the Company entered into the Perceptive Credit Agreement, which included an embedded derivative that required bifurcation related to early repayment provision. This embedded derivative fair value of $0.2 million was recorded as debt issuance discount. Refer to Note 10 for additional details. The derivative is remeasured at the end of each reporting period if debt remains outstanding with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the condensed consolidated statements of operations.
Revenue	Revenue The Company recognizes revenue from testing services, products, and license and other revenue in the amount that reflects the consideration which it expects to be entitled in exchange for goods or services as it transfers control to its customers. Revenue is recorded considering a five-step model that includes identifying the contract with a customer, identifying the performance obligations in the contract, determining the transaction price, allocating the transaction price to the performance obligations, and recognizing revenue when, or as, an entity satisfies a performance obligation. Testing Services Revenue AlloMap and AlloSure patient tests are ordered by healthcare providers. The Company receives a test requisition form with payer information along with a collected patient blood sample. The Company considers the patient to be its customer and the test requisition form a contract. Testing services are performed in the Company’s laboratory. Testing services represent one performance obligation in a contract and are performed when results of the test are provided to the healthcare provider, at a point of time. The healthcare providers that order the tests and on whose behalf CareDx provides testing services are generally not responsible for the payment of these services. The first and second revenue recognition criteria are satisfied when the Company receives a test requisition form with payer information from the healthcare provider. Generally, the Company bills third-party payers upon delivery of an AlloMap or AlloSure test result to the healthcare provider. Amounts received may vary amongst payers based on coverage practices and policies of the payer. The Company has used the portfolio approach, a practical expedient under Accounting Standards Codifications (“ASC”) Topic 606, to identify financial classes of payers. Transaction prices are determined for each financial class using history of reimbursements, including analysis of an average reimbursement per test and a percentage of tests reimbursed. The Company estimates revenue for non-contracted payers and self-payers using this methodology. The estimate requires significant judgment. Revenue recognized for Medicare and other contracted payers is based on the agreed current reimbursement rate per test, adjusted for historical collection trends where applicable. The Company monitors revenue estimates at each reporting period based on actual cash collections in order to assess whether a revision to the estimate is required. Changes in transaction price estimates are updated quarterly based on actual cash collected or changes made to contracted rates.
Product Revenue	Product Revenue Product revenue is recognized from the sale of products to end-users, distributors and strategic partners when all revenue recognition criteria are satisfied. The Company generally has a contract or a purchase order from a customer with the specified required terms of order, including the number of products ordered. Transaction prices are determinable and products are delivered and risk of loss passed to the customer upon either shipping or delivery, as per the terms of the agreement. There are no further performance obligations related to a contract and revenue is recognized at the point of delivery consistent with the terms of the contract or purchase order.
License and Other Revenue	License and Other Revenue The Company generates revenue from license agreements. License agreements may include non-refundable upfront payments, partial or complete reimbursement of research and development costs, contingent payments based on the occurrence of specified events under the agreements, license fees and royalties on sales of products or product candidates if they are successfully commercialized. The Company’s performance obligations under the agreements may include the transfer of intellectual property rights in the form of licenses, obligations to provide research and development services and obligations to participate on certain development committees. The Company makes judgments to determine if performance obligations are distinct or should be combined and the transaction price allocated to each performance obligation, which affect the periods over which revenue is recognized. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any change in estimated periods of performance on a prospective basis. The Company constrains variable consideration, such as milestones, if it is probable that a significant portion of revenue would be reversed. The Company’s deferred revenue relates to one performance obligation, which should be recognized over time. The Company did not recognize any revenue connected with milestones during the three or six months ended June 30, 2018 or 2017.
Cost of Testing Services	Cost of Testing Services Cost of testing services reflects the aggregate costs incurred in delivering the Company’s testing services. The components of cost of testing are materials and service costs, direct labor costs, stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples, and allocated overhead including rent, information technology, equipment depreciation, utilities and royalties. Prior to adoption of the new revenue guidance, the Company recorded costs of testing associated with performing tests (except royalties) in the period when tests were performed without consideration of whether revenue was recognized in the same period. With the adoption of the new revenue standard on January 1, 2018, revenue and cost of testing for tests performed are recognized in the same period. Royalties for licensed technology, calculated as a percentage of test revenues, are recorded as license fees in cost of testing services at the time the test revenues are recognized.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2018, the Company adopted the new revenue accounting standard Revenue from Contracts with Customers (Topic 606) The adoption of ASC 606 resulted in a one-time adjustment of $2.9 million to accounts receivable and retained earnings on January 1, 2018. The adjustment reflects the estimated payments to be received for tests where the result had been delivered at December 31, 2017, but associated revenue had not been recognized by December 31, 2017, because payment had not been received. The new standard did not impact the Company’s product revenue or license and other revenue, nor did it impact contract assets or contract liabilities. The following table summarizes the impact of the ASC 606 adoption on accounts receivable as of June 30, 2018 (in thousands): Balance as Reported Balance without the adoption of ASC 606 Impact of Adoption of ASC 606 Balance Sheets Accounts Receivable $ 8,072 $ 4,564 $ 3,508 The following table summarizes the impact to the statement of operations in accordance with the new revenue standard requirements for the three and six months ended June 30, 2018 (in thousands): Three Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 13,997 $ 13,484 $ 513 Product revenue 3,550 3,550 — License and other revenue 276 276 — $ 17,823 $ 17,310 $ 513 Six Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 24,601 $ 24,076 $ 525 Product revenue 6,857 6,857 — License and other revenue 418 418 — $ 31,876 $ 31,351 $ 525 In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (Topic 842), Codification Improvements to Topic 842, Leases. Leases (Topic 842): Targeted Improvements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force) . In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting In July 2017, the FASB issued ASU No. 2017-11, Accounting for Certain Financial Instruments with Down Round Features and Replacement of the Indefinite Deferral of Mandatorily Redeemable Financial Instruments of Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception In February 2018, the FASB issued ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share Based Payment Accounting

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
ASU 2014-09 [Member]
Schedule of Impact to Statement of Operations and Balance Sheets in Accordance with New Revenue Standard Requirements	The following table summarizes the impact of the ASC 606 adoption on accounts receivable as of June 30, 2018 (in thousands): Balance as Reported Balance without the adoption of ASC 606 Impact of Adoption of ASC 606 Balance Sheets Accounts Receivable $ 8,072 $ 4,564 $ 3,508 The following table summarizes the impact to the statement of operations in accordance with the new revenue standard requirements for the three and six months ended June 30, 2018 (in thousands): Three Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 13,997 $ 13,484 $ 513 Product revenue 3,550 3,550 — License and other revenue 276 276 — $ 17,823 $ 17,310 $ 513 Six Months Ended June 30, 2018 Balance As Reported Balance without the adoption of ASC 606 Revenue Impact of adoption of ASC 606 Statements of Operations Testing revenue $ 24,601 $ 24,076 $ 525 Product revenue 6,857 6,857 — License and other revenue 418 418 — $ 31,876 $ 31,351 $ 525

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share	The following tables set forth the computation of the Company’s basic and diluted net loss per share (in thousands, except shares and per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator: Net loss attributable to CareDx, Inc. used to compute basic and diluted net loss per share $ (14,062 ) $ (3,968 ) $ (23,031 ) $ (9,530 ) Denominator: Weighted-average shares used to compute basic and diluted net loss per share attributable to CareDx, Inc. 35,549,837 21,412,480 32,599,032 21,378,321 Net loss per share attributable to CareDx, Inc.: Basic and diluted $ (0.40 ) $ (0.19 ) $ (0.71 ) $ (0.45 )
Potentially Dilutive Securities Excluded from Diluted Net Loss Per Share	The following potentially dilutive securities have been excluded from diluted net loss per share, because their effect would be antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Shares of common stock subject to outstanding options 2,561,458 1,898,389 2,561,458 1,898,389 Shares of common stock subject to outstanding common stock warrants 3,328,089 4,509,926 3,328,089 4,509,926 Shares of common stock subject to convertible notes — 6,092,105 — 6,092,105 Shares of common stock subject to contingent consideration — 227,845 — 227,845 Restricted stock units 896,904 353,807 896,904 353,807 Total common stock equivalents 6,786,451 13,082,072 6,786,451 13,082,072

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table sets forth the Company’s financial assets and liabilities measured at fair value on a recurring basis, as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 12,958 $ — $ — $ 12,958 Liabilities Common stock warrant liability — — 16,800 16,800 Perceptive derivative liability — — 235 235 Total liabilities $ — $ — $ 17,035 $ 17,035 December 31, 2017 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 13,097 $ — $ — $ 13,097 Liabilities Contingent consideration $ — $ — $ 1,672 $ 1,672 Common stock warrant liability — — 18,712 18,712 JGB derivative liability — — 14,600 14,600 Total liabilities $ — $ — $ 34,984 $ 34,984
Summary of Issuances, Changes in Fair Value and Reclassifications of Level 3 Financial Instruments	The following table presents the issuances, changes in fair value and reclassifications of the Company’s Level 3 financial instruments that are measured at fair value on a recurring basis (in thousands): (Level 3) Contingent Consideration Liability Common JGB Derivative Liability Perceptive Derivative Liability Total Balance as of December 31, 2017 $ 1,672 $ 18,712 $ 14,600 — $ 34,984 Exercise of warrants — (127 ) — — (127 ) Conversion of JGB debt to common stock (Note 10) — — (12,066 ) — (12,066 ) Reclassification to equity (Note 2) — (6,550 ) — — (6,550 ) Issuance of Perceptive derivative liability — — — 235 235 Change in estimated fair value (1,672 ) 4,765 (2,534 ) — 559 Balance as of June 30, 2018 $ - $ 16,800 $ — $ 235 $ 17,035
Summary of Common Stock Warrant Liability and Derivative Liability Valuation Assumptions	Common Stock Warrant Liability and Derivative Liability Valuation Assumptions June 30, 2018 December 31, 2017 Private Placement Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 1.12 $ 1.12 Remaining term (in years) 4.79 5.29 Volatility 75.00 % 66.00 % Risk-free interest rate 2.68 % 2.21 % Subsequent Financing Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 4.00 $ 4.00 Remaining term (in years) 4.96 5.46 Volatility 75.00 % 65.00 % Risk-free interest rate 2.69 % 2.21 % Placement Agent Common Stock Warrant Liability Stock Price $ 12.24 $ 7.34 Exercise Price $ 1.12 $ 1.12 Remaining term (in years) 2.79 3.29 Volatility 87.00 % 82.00 % Risk-free interest rate 2.57 % 1.99 % Perceptive Derivative Liability Remaining term (in years) 4.80 — Discount rate 7.50 % — % JGB Common Stock Warrant Liability Stock Price — $ 7.34 Exercise Price — $ 4.67 Remaining term (in years) — 4.71 Volatility — % 69.00 % Risk-free interest rate — % 1.89 % JGB Derivative Liability Stock Price — $ 7.34 Remaining term (in years) — 2.16 Volatility — % 69.00 % Risk-free interest rate — % 2.14 %

Business Combinations and Ass28

Business Combinations and Asset Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2018
Illumina [Member]
Summary of Fair Values of Assets Acquired and Liabilities Assumed as of Acquisition Date	The following table summarizes the fair values of the intangible assets acquired as of the closing date (in thousands): Estimated Fair Value Estimated Useful Lives (Years) Customer relationships: TruSight HLA $ 380 2.6 Acquired in-process technology: AlloSeq HLA 2,719 — Acquired in-process technology: AlloSeq BMT 2,103 — Total $ 5,202

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	The following tables present details of the Company’s intangible assets as of June 30, 2018 (in thousands): June 30, 2018 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Net Amount Remaining Useful (In Intangible assets with finite lives: Customer relationships: Allenex $ 12,650 $ (1,810 ) $ (1,117 ) $ 9,723 12.5 Customer relationships: Conexio 28 (5 ) (1 ) 22 7.6 Customer relationships: TruSight HLA 380 (12 ) — 368 2.5 Developed technology: Olerup SSP 11,650 (2,524 ) (987 ) 8,139 7.5 Acquired technology: Olerup QTYPE 4,510 (528 ) (402 ) 3,580 12.5 Acquired technology: Olerup SBT 127 (21 ) (6 ) 100 7.6 Acquired technology: dd-cfDNA 6,650 (381 ) — 6,269 12.3 Trademarks 2,260 (384 ) (139 ) 1,737 12.5 Total intangible assets with finite lives $ 38,255 $ (5,665 ) $ (2,652 ) $ 29,938 Acquired in-process technology: AlloSeq HLA 2,719 — — 2,719 — Acquired in-process technology: AlloSeq BMT 2,103 — — 2,103 — Total intangible assets $ 43,077 $ (5,665 ) $ (2,652 ) $ 34,760 The following tables present details of the Company’s intangible assets as of December 31, 2017 (in thousands): December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Net Amount Remaining Useful (In Customer relationships: Allenex $ 12,650 $ (1,394 ) $ (250 ) $ 11,006 13.0 Customer relationships: Conexio 28 (3 ) 1 26 8.1 Developed technology: Olerup SSP 11,650 (1,942 ) (258 ) 9,450 8.0 Acquired technology: Olerup QTYPE 4,510 (376 ) (84 ) 4,050 13.0 Acquired technology: Olerup SBT 127 (14 ) 5 118 8.1 Acquired technology: dd-cfDNA 6,650 (127 ) — 6,523 12.9 Trademarks 2,260 (310 ) 16 1,966 13.0 Total intangible assets $ 37,875 $ (4,166 ) $ (570 ) $ 33,139
Summary of Estimated Future Amortization Expense of Intangible Assets	The following table summarizes the Company’s estimated future amortization expense of intangible assets with finite lives as of June 30, 2018 (in thousands): Years Ending December 31, Cost of Product Sales and Marketing Total Remainder of 2018 $ 949 $ 533 $ 1,482 2019 1,893 1,067 2,960 2020 1,893 1,067 2,960 2021 1,893 920 2,813 2022 1,893 920 2,813 2023 1,893 920 2,813 Thereafter 7,673 6,424 14,097 Total future amortization expense $ 18,087 $ 11,851 $ 29,938

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Inventory	Inventory consisted of the following (in thousands): June 30, 2018 December 31, 2017 Finished goods $ 1,379 $ 2,569 Work in progress 1,548 1,471 Raw materials 1,739 1,489 Total inventory $ 4,666 $ 5,529
Components of Accrued and Other Liabilities	Accrued and other liabilities Accrued and other liabilities consisted of the following (in thousands): June 30, 2018 December 2017 Clinical studies $ 1,580 $ 1,115 Test sample processing fees 614 633 Shares withheld in lieu of taxes 557 — Deferred rent – current portion 419 419 Professional fees 398 475 Customer overpayments and refunds due 259 270 Capital leases – current portion 139 13 Accrued royalty 159 — Software implementation costs 50 94 Accrued interest payable 37 81 Other accrued expenses 491 635 Total accrued and other liabilities $ 4,703 $ 3,735

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Lease Commitments under Operating and Capital Leases	Future minimum lease commitments under these operating and capital leases on June 30, 2018, are as follows (in thousands): Years Ending December 31, Capital Leases Operating Leases Remainder of 2018 $ 85 $ 1,111 2019 162 2,133 2020 157 2,046 2021 45 10 2022 — 7 Total future minimum lease payments $ 449 $ 5,307

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Schedule of Debt	Debt consisted of the following (in thousands): June 30, 2018 December JGB Debt $ — $ 7,743 Danske Bank Credit Facility — 6,763 SSP Primers Loan — 1,215 Current portion of long-term debt $ — $ 15,721 Perceptive Credit Agreement $ 13,337 $ — JGB Debt — 14,168 Danske Bank Term Loan — — FastPartner Subordinated Promissory Notes — 2,400 Al Amoudi Subordinated Promissory Notes — 1,770 Long-term debt, net of current portion $ 13,337 $ 18,338
Schedule of Maturities of Debt	As of June 30, 2018, future debt maturities were as follows (in thousands): Years Ending December 31, Amount 2021 $ 2,025 2022 2,700 2023 10,275 Total debt maturities 15,000 Less: debt discount and issuance costs (1,663 ) Long-term debt, net carrying value 13,337
Perceptive Security Agreement [Member]
Schedule of Carrying Values of Debt	The following table summarizes the Company’s carrying value of the Perceptive Security Agreement (in thousands) on April 17, 2018, the issuance date (in thousands): April 17, 2018 Debt principal $ 15,000 Less: Issuance cost (669 ) Discount related to issued warrants (784 ) Embedded derivative liability (245 ) Total debt discount (1,698 ) Carrying value $ 13,302
JGB Debt [Member]
Schedule of Carrying Values of Debt	The following table summarizes the Company’s carrying value of the JGB Debt (in thousands) on the March 15, 2017 issuance date: March 15, 2017 Debt principal $ 27,780 Less: Issuance cost (998 ) Original issue discount (2,780 ) Original warrant valuation (900 ) Embedded Derivative Liability (2,290 ) Total debt discount (6,968 ) Carrying value $ 20,812

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2018
Common Stock [Member]
Class Of Warrant Or Right [Line Items]
Components of Warrants Outstanding	As of June 30, 2018, outstanding warrants to purchase common stock were: Classified as Original Term Exercise Price Number of Shares Underlying Warrants Original issue date: August 2009 Equity 10 years $ 21.78 33,473 July 2010 Equity 9 years $ 21.78 6,694 August 2012 Equity 7 years $ 21.78 167,182 January 2015 Equity 5 years $ 6.96 34,483 April 2016 (a) Liability 7 years $ 1.12 469,124 April 2016 (b) Liability 5 years $ 1.12 136,300 June 2016 (c) Liability 7 years $ 4.00 1,002,507 March 2017 (d) Equity 5 years $ 4.67 1,338,326 April 2018 (e) Equity 7 years $ 8.60 140,000 April 2018 (f) Equity 7 years $ 8.60 93,333 3,421,422 (a) Issued on April 14, 2016 in connection with the private placement to certain accredited investors. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with such private placement was adjusted from $4.98 to $4.00, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $4.00 to $1.12, effective July 3, 2017. (b) Issued on April 14, 2016 in connection with the private placement to placement agents. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $3.99 to $1.12, effective July 3, 2017. (c) Issued on June 15, 2016 in connection with a subsequent private placement. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with the subsequent private placement was adjusted from $4.98 per share to $4.00 per share, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. The exercise price remained at $4.00 as the anti-dilution provision was waived for the issuance of shares related to the July 3, 2017 amendment to the Conditional Share Purchase Agreements. (d) Issued on March 15, 2017 in connection with the JGB Debt. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the number of shares issuable pursuant to the JGB Warrants increased from 1,250,000 to 1,296,679 and the exercise price of the JGB Warrants was adjusted from $5.00 to $4.82, effective July 3, 2017. As a result of the 2017 Public Offering, effective October 5, 2017, the aggregate number of shares of common stock issuable upon exercise of the JGB Warrants increased from 1,296,679 to 1,338,326 shares and the exercise price of the JGB Warrants decreased from $4.82 to $4.67 per share. (e) Issued on April 17, 2018 in connection with the Perceptive Credit Agreement. (f) The Perceptive Credit Agreement included a Tranche B loan amount

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Option, Unvested RSU Activity under 2014 Equity Incentive Plan and 2016 Inducement Plan and Related Information	The following table summarizes option and unvested RSU activity under the Company’s 2014 Equity Incentive Plan and 2016 Inducement Plan and related information: Shares Available for Grant Stock Options Outstanding Weighted- Average Exercise Price Number of RSU Shares Weighted- Average Grant Date Fair Value Balance—December 31, 2017 156,429 1,941,473 $ 4.21 439,926 $ 4.39 Additional options authorized 1,957,075 — — — — Restricted stock grants (17,919 ) — — — — RSUs granted (714,834 ) — — 714,834 11.63 RSUs forfeited 13,050 — — (13,050 ) 4.87 RSUs vested — — — (244,806 ) 9.30 Repurchases of common stock under employee incentive plans 67,656 Options granted (809,634 ) 809,634 11.05 — — Options exercised — (167,379 ) 1.07 — — Options forfeited 20,453 (20,453 ) 4.78 — — Options expired 1,817 (1,817 ) 3.55 — — Balance—June 30, 2018 674,093 2,561,458 $ 6.57 896,904 $ 8.83
Summary of Options Outstanding and Exercisable Vested or Expected to Vest	Options outstanding that have vested and are expected to vest at June 30, 2018 are as follows: Number of Shares Weighted Exercise Price Weighted Aggregate Intrinsic (In Vested 991,627 $ 6.57 6.73 $ 7,400 Expected to vest 1,360,609 7.83 7.54 6,191 Total 2,352,236 $ 13,591
Weighted-Average Assumptions Used to Estimate Fair Value of Share-Based Awards	The estimated fair values of employee stock options and ESPP shares were estimated using the Black-Scholes option-pricing model based on the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Employee stock options Expected term (in years) 6.0 6.0 6.0 6.0 Expected volatility 66.00 % 55.46-57.71% 68.75 % 53.07%-57.71% Risk-free interest rate 2.76 % 1.90-1.96% 2.71 % 1.90%-2.12% Expected dividend yield — % — % — % — % Employee stock purchase plan Expected term (in years) 0.5 0.5 0.5 0.5 Expected volatility 105.32 % 62.27 % 105.32 % 62.27 % Risk-free interest rate 1.61 % 0.65 % 1.61 % 0.65 % Expected dividend yield — % — % — % — %
Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs	The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs and ESPP shares for the three and six months ended June 30, 2018 and 2017, included in the statements of operations as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of testing $ 191 $ 63 $ 252 $ 119 Research and development 462 111 675 175 Sales and marketing 466 57 529 95 General and administrative 1,393 264 1,761 497 Total $ 2,512 $ 495 $ 3,217 $ 886

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Operating Results of Reportable Segments	The following table summarizes the operating results of the Company’s reportable segments (in thousands): Three Six Months Ended June 30, 2018 2017 2018 2017 Total Segments Revenues $ 17,823 $ 12,046 $ 31,876 $ 23,630 Operating loss (5,209 ) (3,599 ) (10,444 ) (12,143 ) Depreciation and amortization 986 887 2,025 1,821 Post-Transplant Revenues $ 14,171 $ 8,670 $ 24,917 $ 16,587 Operating loss (3,138 ) (2,662 ) (6,333 ) (8,121 ) Depreciation and amortization 316 236 645 498 Pre-Transplant Revenues $ 3,652 $ 3,376 $ 6,959 $ 7,043 Operating loss (2,071 ) (937 ) (4,111 ) (4,022 ) Depreciation and amortization 670 651 1,380 1,323 June 30, December Assets: Post-Transplant $ 48,851 $ 48,734 Pre-Transplant 31,028 34,831 Total assets $ 79,879 $ 83,565
Reportable Revenues by Geographic Regions	Revenues by geographic regions are based upon the customers’ ship-to address for pre-transplant product revenues and the region of testing for post-transplant service revenue. The following table summarizes reportable revenues by geographic regions (in thousands): Three Three Post-Transplant Pre-Transplant Post-Transplant Pre-Transplant Revenues: North America $ 14,147 $ 1,489 $ 8,647 $ 983 Europe 24 1,856 23 1,863 Australia — 31 — 125 Rest of the World — 276 — 405 Total $ 14,171 $ 3,652 $ 8,670 $ 3,376 Six Six Post-Transplant Pre-Transplant Post-Transplant Pre-Transplant Revenues: North America $ 24,876 $ 2,418 $ 16,549 $ 1,983 Europe 41 3,829 38 3,922 Australia — 105 — 241 Rest of the World — 607 — 897 Total $ 24,917 $ 6,959 $ 16,587 $ 7,043
Long-Lived Assets Consisting of Property and Equipment, Net by Geographic Regions	The following table summarizes long-lived assets, consisting of property and equipment, net, by geographic regions (in thousands): June 30, 2018 December Long-lived assets: North America $ 1,572 $ 1,206 Europe 708 776 Australia 80 93 Total $ 2,360 $ 2,075

Organization and Description 36

Organization and Description of Business - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)Segment	Apr. 17, 2018USD ($)	Dec. 31, 2017USD ($)
Schedule of Capitalization, Equity [Line Items]
Number of reportable segments | Segment	2
Accumulated deficit	$ 288,120,000		$ 268,022,000
Cash and cash equivalents	16,246,000		16,895,000
Debt outstanding, net of debt discount, under debt obligations	13,300,000
Current debt	$ 0		$ 15,721,000
Perceptive Credit Agreement [Member]
Schedule of Capitalization, Equity [Line Items]
Aggregate principal amount		$ 15,000,000
Perceptive Credit Agreement [Member] | Tranche B Term Loan [Member]
Schedule of Capitalization, Equity [Line Items]
Aggregate principal amount		$ 10,000,000

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Apr. 17, 2018	Mar. 31, 2018	Mar. 15, 2017
Summary Of Significant Accounting Policies [Line Items]
Revenue recognition under milestone method		$ 0	$ 0	$ 0	$ 0
ASU 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings and accounts receivable	$ 2,900,000
JGB Debt [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash released upon full conversion of debt obligation							$ 9,400,000
Debt issuance discount								$ 2,780,000
JGB Debt [Member] | ASU 2017-11 [Member]
Summary Of Significant Accounting Policies [Line Items]
Reclassification of warrant liability to equity	$ 6,600,000
Perceptive Credit Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Debt issuance discount						$ 200,000
Allenex [Member]
Summary Of Significant Accounting Policies [Line Items]
Acquisition date				Apr. 14, 2016
Allenex [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Company ownership percentage		100.00%		100.00%

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Additional Information - Concentration of Credit Risk (Detail)	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Services Revenue [Member] | Customer Concentration Risk [Member] | Minimum [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%		10.00%
Services Revenue [Member] | Customer Concentration Risk [Member] | Medicare [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	45.00%	28.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Minimum [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%		10.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Medicare [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%		16.00%

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Summary of Impact of ASC 606 Adoption on Account Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Balance Sheets
Accounts receivable	$ 8,072	$ 2,991
ASU 2014-09 [Member]
Balance Sheets
Accounts receivable	8,072
ASU 2014-09 [Member] | Balances Without the Adoption of ASC 606 [Member]
Balance Sheets
Accounts receivable	4,564
ASU 2014-09 [Member] | Impact Adoption of ASC 606 [Member]
Balance Sheets
Accounts receivable	$ 3,508

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Summary of Impact to Statement of Operations in Accordance with New Revenue Standard Requirements (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statements of Operations
Total revenue	$ 17,823	$ 12,046	$ 31,876	$ 23,630
Product [Member]
Statements of Operations
Total revenue	3,550	3,376	6,857	7,043
License and Other [Member]
Statements of Operations
Total revenue	276	$ 250	418	$ 265
ASU 2014-09 [Member]
Statements of Operations
Total revenue	17,823		31,876
ASU 2014-09 [Member] | Balances Without the Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	17,310		31,351
ASU 2014-09 [Member] | Impact Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	513		525
ASU 2014-09 [Member] | Testing [Member]
Statements of Operations
Total revenue	13,997		24,601
ASU 2014-09 [Member] | Testing [Member] | Balances Without the Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	13,484		24,076
ASU 2014-09 [Member] | Testing [Member] | Impact Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	513		525
ASU 2014-09 [Member] | Product [Member]
Statements of Operations
Total revenue	3,550		6,857
ASU 2014-09 [Member] | Product [Member] | Balances Without the Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	3,550		6,857
ASU 2014-09 [Member] | Product [Member] | Impact Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	0		0
ASU 2014-09 [Member] | License and Other [Member]
Statements of Operations
Total revenue	276		418
ASU 2014-09 [Member] | License and Other [Member] | Balances Without the Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	276		418
ASU 2014-09 [Member] | License and Other [Member] | Impact Adoption of ASC 606 [Member]
Statements of Operations
Total revenue	$ 0		$ 0

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net loss attributable to CareDx, Inc. used to compute basic and diluted net loss per share	$ (14,062)	$ (3,968)	$ (23,031)	$ (9,530)
Denominator:
Weighted-average shares used to compute basic and diluted net loss per share attributable to CareDx, Inc.	35,549,837	21,412,480	32,599,032	21,378,321
Net loss per share attributable to CareDx, Inc.:
Basic and diluted	$ (0.40)	$ (0.19)	$ (0.71)	$ (0.45)

Net Loss Per Share - Potentiall

Net Loss Per Share - Potentially Dilutive Securities Excluded from Diluted Net Loss Per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	6,786,451	13,082,072	6,786,451	13,082,072
Shares of common stock subject to outstanding options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	2,561,458	1,898,389	2,561,458	1,898,389
Shares of common stock subject to outstanding common stock warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	3,328,089	4,509,926	3,328,089	4,509,926
Shares of common stock subject to convertible notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	0	6,092,105	0	6,092,105
Shares of common stock subject to contingent consideration [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	0	227,845	0	227,845
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share attributable to common stockholders, Total	896,904	353,807	896,904	353,807

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Detail)	Oct. 10, 2017shares	Jul. 01, 2017shares	Jun. 30, 2018CommercialTestshares	Mar. 31, 2018shares	Jun. 30, 2018shares	Dec. 31, 2017shares	Apr. 17, 2018USD ($)shares
Contingent Consideration Liability [Member] | ImmuMetrix, Inc. [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Number of completed commercial tests | CommercialTest			2,500
Number of shares issued pursuant to contingent consideration			227,845		227,845
JGB Debt [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Shares issued upon conversion		1,022,544		6,415,039		6,415,039
Perceptive Credit Agreement [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Aggregate principal amount | $							$ 15,000,000
Perceptive Credit Agreement [Member] | Tranche B Term Loan [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Aggregate principal amount | $							$ 10,000,000
Perceptive Credit Agreement [Member] | Tranche B Term Loan [Member] | Maximum [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Warrant to purchase stock, shares							93,333
Underwritten Public Offering [Member]
Schedule of Net Income (Loss) Per Share [Line Items]
Common stock shares issued	4,992,840

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Money market funds	$ 12,958	$ 13,097
Liabilities
Common stock warrant liability	16,800	18,712
Total liabilities	17,035	34,984
Contingent consideration		1,672
Perceptive Derivative Liability [Member]
Liabilities
Derivative liability	235
JGB Derivative Liability [Member]
Liabilities
Derivative liability		14,600
Fair Value Measured Using - (Level 1) [Member]
Assets
Money market funds	12,958	13,097
Liabilities
Common stock warrant liability	0	0
Total liabilities	0	0
Contingent consideration		0
Fair Value Measured Using - (Level 1) [Member] | Perceptive Derivative Liability [Member]
Liabilities
Derivative liability	0
Fair Value Measured Using - (Level 1) [Member] | JGB Derivative Liability [Member]
Liabilities
Derivative liability		0
Fair Value Measured Using - (Level 2) [Member]
Assets
Money market funds	0	0
Liabilities
Common stock warrant liability	0	0
Total liabilities	0	0
Contingent consideration		0
Fair Value Measured Using - (Level 2) [Member] | Perceptive Derivative Liability [Member]
Liabilities
Derivative liability	0
Fair Value Measured Using - (Level 2) [Member] | JGB Derivative Liability [Member]
Liabilities
Derivative liability		0
Fair Value Measured Using - (Level 3) [Member]
Assets
Money market funds	0	0
Liabilities
Common stock warrant liability	16,800	18,712
Total liabilities	17,035	34,984
Contingent consideration		1,672
Fair Value Measured Using - (Level 3) [Member] | Perceptive Derivative Liability [Member]
Liabilities
Derivative liability	$ 235
Fair Value Measured Using - (Level 3) [Member] | JGB Derivative Liability [Member]
Liabilities
Derivative liability		$ 14,600

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Issuances, Changes in Fair Value and Reclassifications of Level 3 Financial Instruments (Detail) - Fair Value Measured Using - (Level 3) [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	$ 34,984
Exercise of warrants	(127)
Conversion of JGB debt to common stock (Note 10)	(12,066)
Reclassification to equity (Note 2)	(6,550)
Issuance of Perceptive derivative liability	235
Change in estimated fair value	559
Ending Balance	17,035
Common Stock Warrant Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	18,712
Exercise of warrants	(127)
Conversion of JGB debt to common stock (Note 10)	0
Reclassification to equity (Note 2)	(6,550)
Issuance of Perceptive derivative liability	0
Change in estimated fair value	4,765
Ending Balance	16,800
Contingent Consideration Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	1,672
Exercise of warrants	0
Conversion of JGB debt to common stock (Note 10)	0
Reclassification to equity (Note 2)	0
Issuance of Perceptive derivative liability	0
Change in estimated fair value	(1,672)
Ending Balance	0
JGB Derivative Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	14,600
Exercise of warrants	0
Conversion of JGB debt to common stock (Note 10)	(12,066)
Reclassification to equity (Note 2)	0
Issuance of Perceptive derivative liability	0
Change in estimated fair value	(2,534)
Ending Balance	0
Perceptive Derivative Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	0
Exercise of warrants	0
Conversion of JGB debt to common stock (Note 10)	0
Reclassification to equity (Note 2)	0
Issuance of Perceptive derivative liability	235
Change in estimated fair value	0
Ending Balance	$ 235

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014shares	Jun. 30, 2018USD ($)shares	Mar. 27, 2018USD ($)	Jun. 30, 2018USD ($)CommercialTestshares	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)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
Contingent consideration liability outstanding		$ 0		$ 0		$ 1,672,000
JGB Debt Derivative Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair market value of derivative liability			$ 2,500,000		$ 1,300,000
Perceptive Credit Agreement Derivative Liability [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair market value of derivative liability		$ 100,000
ImmuMetrix, Inc. [Member] | Contingent Consideration Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent obligation issuable / issued common stock | shares	227,845					227,845
Number of shares issued pursuant to contingent consideration | shares		227,845		227,845
Milestone description				The shares were issuable upon the Company completing 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
Number of achieved contingent consideration milestone of commercial tests | CommercialTest				2,500
Percentage of probability in achieving contingency condition				100.00%
Contingent consideration liability outstanding		$ 0		$ 0
Perceptive Credit Agreement [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt, carrying value		$ 13,300,000		$ 13,300,000

Fair Value Measurements - Sum47

Fair Value Measurements - Summary of Common Stock Warrant Liability and Derivative Liability Valuation Assumptions (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2018$ / shares	Dec. 31, 2017$ / shares
Private Placement Common Stock Warrant Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price	$ 12.24	$ 7.34
Private Placement Common Stock Warrant Liability [Member] | Exercise Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise Price	$ 1.12	$ 1.12
Private Placement Common Stock Warrant Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	4 years 9 months 14 days	5 years 3 months 14 days
Private Placement Common Stock Warrant Liability [Member] | Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	75	66
Private Placement Common Stock Warrant Liability [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	2.68	2.21
Placement Agent Common Stock Warrant Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price	$ 12.24	$ 7.34
Placement Agent Common Stock Warrant Liability [Member] | Exercise Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise Price	$ 1.12	$ 1.12
Placement Agent Common Stock Warrant Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	2 years 9 months 14 days	3 years 3 months 14 days
Placement Agent Common Stock Warrant Liability [Member] | Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	87	82
Placement Agent Common Stock Warrant Liability [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	2.57	1.99
JGB Common Stock Warrant Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price	$ 0	$ 7.34
JGB Common Stock Warrant Liability [Member] | Exercise Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise Price	$ 0	$ 4.67
JGB Common Stock Warrant Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	0 years	4 years 8 months 15 days
JGB Common Stock Warrant Liability [Member] | Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	0	69
JGB Common Stock Warrant Liability [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	0	1.89
Majority Shareholder Common Stock Warrant Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price	$ 12.24	$ 7.34
Majority Shareholder Common Stock Warrant Liability [Member] | Exercise Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise Price	$ 4	$ 4
Majority Shareholder Common Stock Warrant Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	4 years 11 months 15 days	5 years 5 months 15 days
Majority Shareholder Common Stock Warrant Liability [Member] | Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	75	65
Majority Shareholder Common Stock Warrant Liability [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	2.69	2.21
Perceptive Derivative Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	4 years 9 months 18 days	0 years
Perceptive Derivative Liability [Member] | Discount Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	7.50	0
JGB Derivative Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price	$ 0	$ 7.34
JGB Derivative Liability [Member] | Remaining Term (in Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	0 years	2 years 1 month 28 days
JGB Derivative Liability [Member] | Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	0	69
JGB Derivative Liability [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative liability, measurement input	0	2.14

Business Combinations and Ass48

Business Combinations and Asset Acquisitions - Additional Information (Detail)	May 04, 2018USD ($)	Nov. 14, 2017USD ($)	Jul. 01, 2017USD ($)$ / sharesshares	Jan. 20, 2017USD ($)	Jan. 01, 2017	Apr. 14, 2016USD ($)shares	Apr. 14, 2016SEK (kr)shares	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jul. 05, 2017USD ($)	Apr. 14, 2016kr / shares
Business Acquisition [Line Items]
Business acquisition deferred payment consideration								$ 0	$ 1,064,000
Discount Rate [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Rate used in estimating fair value	18
Illumina [Member]
Business Acquisition [Line Items]
Initial cash payment under license agreement	$ 5,000,000
Illumina [Member] | Discount Rate [Member] | Acquired in-process technology AlloSeq [Member] | HLA [Member]
Business Acquisition [Line Items]
Rate used in estimating fair value	30
Illumina [Member] | Discount Rate [Member] | Acquired in-process technology AlloSeq [Member] | BMT [Member]
Business Acquisition [Line Items]
Rate used in estimating fair value	40
Allenex [Member]
Business Acquisition [Line Items]
Percentage of share acquired						98.30%
Total purchase price combination of cash and common stock						$ 34,100,000
Cash distribution to acquire business, gross						$ 26,900,000
Common stock, shares issue | shares						1,375,029	1,375,029
Common stock value						$ 7,200,000
Business acquisition deferred payment consideration						$ 5,700,000	kr 50,620,000
Business acquisition deferred payment date						Mar. 31, 2017	Mar. 31, 2017
Escrow Deposit										$ 8,000,000
Deferred obligation			$ 6,300,000
Business acquisition deferred payment extended date								Jul. 1, 2017
Conversion of deferred obligation into shares			$ 1,100,000
Shares issued upon conversion | shares			1,022,544
Conversion into common stock per share price | $ / shares			$ 1.12
Portion of deferred obligation considered for extended maturity date			$ 2,900,000
Additional repayment amount of deferred obligation			$ 2,100,000
Payable date of deferred obligation additional repayment amount			Dec. 31, 2017
Percentage of accruing interest			10.00%
Percentage of non controlling interest						1.70%
Price per share of Allenex used to determine fair value of non controlling interest | kr / shares											kr 2.48
Allenex [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business acquisition deferred payment extended date			Mar. 31, 2019
Allenex [Member] | Former Majority Shareholders [Member]
Business Acquisition [Line Items]
Business acquisition deferred payment consideration			$ 500,000
Percentage of accruing interest					10.00%
Reduction in deferred obligation			$ 500,000
Allenex [Member] | Former Majority Shareholders [Member] | Conditional Share Purchase Agreement [Member]
Business Acquisition [Line Items]
Deferred purchase consideration including accrued interest paid		$ 4,700,000
Conexio [Member]
Business Acquisition [Line Items]
Cash distribution to acquire business, gross				$ 400,000
Acquisition related quarterly payments, percentage on gross revenue				20.00%
Conexio [Member] | Illumina [Member]
Business Acquisition [Line Items]
Consideration paid for asset acquisition	$ 5,200,000
Asset acquisition cash consideration transferred	5,000,000
Transaction costs related to asset acquisition	$ 200,000
Conexio [Member] | Maximum [Member]
Business Acquisition [Line Items]
Acquisition related quarterly payments on gross revenue				$ 700,000
Periodic quarterly payments on gross revenue								$ 100,000	$ 100,000

Business Combinations and Ass49

Business Combinations and Asset Acquisitions - Summary of Fair Values of Assets Acquired and Liabilities Assumed as of Acquisition Date (Detail) - USD ($) $ in Thousands	May 04, 2018	Jun. 30, 2018
Customer Relationships [Member] | TruSight [Member] | HLA [Member]
Business Acquisition [Line Items]
Estimated fair value of identified intangible assets	$ 380
Estimated useful life of identified intangible asset	2 years 7 months 6 days	2 years 6 months
Illumina [Member]
Business Acquisition [Line Items]
Estimated fair value of identified intangible assets	$ 5,202
Illumina [Member] | Acquired in-process technology AlloSeq [Member] | HLA [Member]
Business Acquisition [Line Items]
Estimated fair value of identified intangible assets	2,719
Illumina [Member] | Acquired in-process technology AlloSeq [Member] | BMT [Member]
Business Acquisition [Line Items]
Estimated fair value of identified intangible assets	$ 2,103

Goodwill and Intangible Asset50

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 12,005,000			$ 12,005,000		$ 12,005,000
Description of annual goodwill impairment test				On January 1, 2017, the Company adopted ASU 2017-04, which eliminated the Step 2 requirement of the goodwill impairment test. Instead, the goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. The Company determined that the decrease in its market capitalization in the first quarter of 2017 constituted an indicator of impairment and therefore a goodwill impairment test was completed as of March 31, 2017.
Goodwill impairment	0	$ 0		$ 0	$ 1,958,000
Amortization expense of intangible assets	600,000	600,000		1,200,000	1,200,000
Cost of Product [Member]
Goodwill And Intangible Assets [Line Items]
Amortization expense of intangible assets	400,000	400,000		700,000	700,000
Sales and marketing expense [Member]
Goodwill And Intangible Assets [Line Items]
Amortization expense of intangible assets	200,000	$ 200,000		500,000	$ 500,000
Post-Transplant [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 12,000,000			$ 12,000,000		$ 12,000,000
Pre-Transplant [Member]
Goodwill And Intangible Assets [Line Items]
Description of goodwill impairment method for fair value determination				determined that the fair value of the Pre-Transplant reporting unit was $3.5 million, which was lower than its carrying value.
Fair value of reporting unit			$ 3,500,000
Reporting unit, discount rate			16.60%
Reporting unit, terminal growth rate			3.20%
Reporting unit, capitalization multiple			$ 7.48
Pre-Transplant [Member] | Maximum [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill impairment			$ 2,000,000

Goodwill and Intangible Asset51

Goodwill and Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	May 04, 2018	Jun. 30, 2018	Dec. 31, 2017
Intangible assets with finite lives:
Gross Carrying Amount		$ 38,255	$ 37,875
Accumulated Amortization		(5,665)	(4,166)
Foreign Currency Translation		(2,652)	(570)
Net Carrying Amount		29,938	33,139
Intangible Assets, Net (Excluding Goodwill)
Total intangible assets, Gross Carrying Amount		43,077
Total intangible assets, Accumulated Amortization		5,665
Total intangible assets, Foreign Currency Translation		2,652
Total intangible assets, net		34,760	33,139
Customer Relationships [Member] | Allenex [Member]
Intangible assets with finite lives:
Gross Carrying Amount		12,650	12,650
Accumulated Amortization		(1,810)	(1,394)
Foreign Currency Translation		(1,117)	(250)
Net Carrying Amount		$ 9,723	$ 11,006
Estimated useful life of identified intangible asset		12 years 6 months	13 years
Customer Relationships [Member] | Conexio [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 28	$ 28
Accumulated Amortization		(5)	(3)
Foreign Currency Translation		(1)	1
Net Carrying Amount		$ 22	$ 26
Estimated useful life of identified intangible asset		7 years 7 months 6 days	8 years 1 month 6 days
Customer Relationships [Member] | TruSight [Member] | HLA [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 380
Accumulated Amortization		(12)
Foreign Currency Translation		0
Net Carrying Amount		$ 368
Estimated useful life of identified intangible asset	2 years 7 months 6 days	2 years 6 months
Developed Technology [Member] | Olerup [Member] | SSP [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 11,650	$ 11,650
Accumulated Amortization		(2,524)	(1,942)
Foreign Currency Translation		(987)	(258)
Net Carrying Amount		$ 8,139	$ 9,450
Estimated useful life of identified intangible asset		7 years 6 months	8 years
Trademarks [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 2,260	$ 2,260
Accumulated Amortization		(384)	(310)
Foreign Currency Translation		(139)	16
Net Carrying Amount		$ 1,737	$ 1,966
Estimated useful life of identified intangible asset		12 years 6 months	13 years
Acquired Technology - QTYPE | Olerup [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 4,510	$ 4,510
Accumulated Amortization		(528)	(376)
Foreign Currency Translation		(402)	(84)
Net Carrying Amount		$ 3,580	$ 4,050
Estimated useful life of identified intangible asset		12 years 6 months	13 years
Acquired Technology SBT [Member] | Olerup [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 127	$ 127
Accumulated Amortization		(21)	(14)
Foreign Currency Translation		(6)	5
Net Carrying Amount		$ 100	$ 118
Estimated useful life of identified intangible asset		7 years 7 months 6 days	8 years 1 month 6 days
Acquired Technology dd-cfDNA [Member]
Intangible assets with finite lives:
Gross Carrying Amount		$ 6,650	$ 6,650
Accumulated Amortization		(381)	(127)
Foreign Currency Translation		0	0
Net Carrying Amount		$ 6,269	$ 6,523
Estimated useful life of identified intangible asset		12 years 3 months 18 days	12 years 10 months 24 days
Acquired in-Process Technology: AlloSeq [Member] | HLA [Member]
Intangible assets with indefinite lives:
Foreign Currency Translation		$ 0
Net Carrying Amount		2,719
Acquired in-Process Technology: AlloSeq [Member] | BMT [Member]
Intangible assets with indefinite lives:
Foreign Currency Translation		0
Net Carrying Amount		$ 2,103

Goodwill and Intangible Asset52

Goodwill and Intangible Assets - Summary of Estimated Future Amortization Expense of Intangible Assets with Finite Lives (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2018	$ 1,482
2,019	2,960
2,020	2,960
2,021	2,813
2,022	2,813
2,023	2,813
Thereafter	14,097
Net Carrying Amount	29,938	$ 33,139
Cost of Product [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2018	949
2,019	1,893
2,020	1,893
2,021	1,893
2,022	1,893
2,023	1,893
Thereafter	7,673
Net Carrying Amount	18,087
Selling and marketing [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2018	533
2,019	1,067
2,020	1,067
2,021	920
2,022	920
2,023	920
Thereafter	6,424
Net Carrying Amount	$ 11,851

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished goods	$ 1,379	$ 2,569
Work in progress	1,548	1,471
Raw materials	1,739	1,489
Total inventory	$ 4,666	$ 5,529

Balance Sheet Components - Comp

Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Clinical studies	$ 1,580	$ 1,115
Test sample processing fees	614	633
Shares withheld in lieu of taxes	557	0
Deferred rent – current portion	419	419
Professional fees	398	475
Customer overpayments and refunds due	259	270
Capital leases – current portion	139	13
Accrued royalty	159	0
Software implementation costs	50	94
Accrued interest payable	37	81
Other accrued expenses	491	635
Total accrued and other liabilities	$ 4,703	$ 3,735

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Jan. 20, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Loss Contingencies [Line Items]
Facility leases expiration period				2,020
Rent expense under non-cancelable operating leases		$ 400,000	$ 400,000	$ 900,000	$ 900,000
Royalties incurred		200,000		200,000
Illumina [Member]
Loss Contingencies [Line Items]
Royalties incurred		0
Conexio [Member]
Loss Contingencies [Line Items]
Acquisition related quarterly payments, percentage on gross revenue	20.00%
Periodic quarterly payments paid			0
Conexio [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Acquisition related quarterly payments on gross revenue	$ 700,000
Periodic quarterly payments paid		$ 100,000		100,000	100,000
Unpaid Royalties [Member]
Loss Contingencies [Line Items]
Royalty expenses			$ 300,000	$ 0	$ 600,000

Commitments and Contingencies56

Commitments and Contingencies - Future Minimum Lease Commitments under Operating and Capital Leases (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
Capital Leases, Remainder of 2018	$ 85
Capital Leases, 2019	162
Capital Leases, 2020	157
Capital Leases, 2021	45
Capital Leases, 2022	0
Total minimum lease payments under capital leases	449
Operating Leases, Remainder of 2018	1,111
Operating Leases, 2019	2,133
Operating Leases, 2020	2,046
Operating Leases, 2021	10
Operating Leases, 2022	7
Total minimum lease payments under operating leases	$ 5,307

License and Other Revenue - Add

License and Other Revenue - Additional Information (Detail)	1 Months Ended			3 Months Ended		6 Months Ended
	Jul. 31, 2013USD ($)	Jun. 30, 2013USD ($)	Jun. 30, 2013EUR (€)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Jun. 30, 2013EUR (€)
License And Other Revenue [Line Items]
Description of agreement expire term						The agreement will expire at the later of the last-to-expire patent in the EEA or ten years from the first commercial sale of the test in the EEA, which occurred in 2014.
Common stock value				$ 36,000		$ 36,000		$ 29,000
Upfront cash payment		$ 408,000	€ 387,500
Revenues and royalties recognized				10,000	$ 10,000	19,000	$ 19,000
Royalty revenues				17,823,000	12,046,000	31,876,000	23,630,000
Royalty revenues receivable balance				0		0		$ 0
Royalty [Member]
License And Other Revenue [Line Items]
Royalty revenues				$ 200,000	$ 200,000	$ 300,000	$ 200,000
Diaxonhit [Member]
License And Other Revenue [Line Items]
Common stock value		$ 476,000							€ 387,500
Shares sold for consideration	$ 467,000

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Current portion of long-term debt	$ 0	$ 15,721,000
Long-term debt, net of current portion	13,337,000	18,338,000
JGB Debt [Member]
Debt Instrument [Line Items]
Current portion of long-term debt	0	7,743,000
Long-term debt, net of current portion	0	14,168,000
Perceptive Credit Agreement [Member]
Debt Instrument [Line Items]
Long-term debt, net of current portion	13,337,000	0
Danske Bank Credit Facility [Member]
Debt Instrument [Line Items]
Current portion of long-term debt	0	6,763,000
Danske Bank Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt, net of current portion	0	0
SSP Primers Loan [Member]
Debt Instrument [Line Items]
Current portion of long-term debt	0	1,215,000
FastPartner Subordinated Promissory Notes [Member]
Debt Instrument [Line Items]
Long-term debt, net of current portion	0	2,400,000
Al Amoudi Subordinated Promissory Notes [Member]
Debt Instrument [Line Items]
Long-term debt, net of current portion	$ 0	$ 1,770,000

Debt - Additional Information (

Debt - Additional Information (Detail)

Apr. 17, 2018USD ($)$ / sharesshares

Apr. 17, 2018SEK (kr)

Mar. 01, 2018

Feb. 28, 2018USD ($)

Feb. 28, 2018SEK (kr)

Oct. 10, 2017$ / sharesshares

Oct. 05, 2017USD ($)$ / sharesshares

Jul. 01, 2017USD ($)$ / sharesshares

Jul. 01, 2017SEK (kr)shares

Mar. 15, 2017USD ($)$ / sharesshares

Mar. 07, 2016USD ($)

Dec. 29, 2015USD ($)

Jun. 18, 2015USD ($)

Feb. 25, 2015USD ($)

Feb. 25, 2015SEK (kr)

Jun. 28, 2013USD ($)

Jun. 25, 2013USD ($)

Oct. 31, 2017USD ($)

Oct. 31, 2017SEK (kr)

Mar. 31, 2018USD ($)shares

Mar. 31, 2018USD ($)shares

Jun. 30, 2018USD ($)

Jun. 30, 2017USD ($)

Dec. 31, 2017USD ($)shares

Jun. 30, 2018SEK (kr)

Apr. 13, 2018

Mar. 31, 2018SEK (kr)

Dec. 31, 2017SEK (kr)

Jul. 03, 2017$ / shares

Aug. 04, 2016USD ($)

Aug. 04, 2016SEK (kr)

Mar. 07, 2016SEK (kr)

Dec. 29, 2015SEK (kr)

Jun. 18, 2015SEK (kr)

Feb. 25, 2015SEK (kr)

Jun. 28, 2013SEK (kr)

Jun. 25, 2013SEK (kr)

Debt Instrument [Line Items]

Unamortized debt discount and issuance costs

$ 1,663,000

$ 4,600,000

Total accrued interest on debt

0

300,000

Current portion of accrued interest

37,000

81,000

Proceeds from debt, net of issuance costs

14,282,000

$ 24,002,000

Loss on debt extinguishment

2,806,000

$ 0

Principal outstanding amount

13,337,000

18,338,000

Allenex [Member]

Debt Instrument [Line Items]

Shares issued upon conversion | shares

1,022,544

1,022,544

Conversion into common stock per share price | $ / shares

$ 1.12

S S P Primers Aktieboulag [Member] | Allenex [Member]

Debt Instrument [Line Items]

Debt instrument maturity date

Feb. 26, 2018

Feb. 26, 2018

Term loan facility amount outstanding

1,200,000

kr 10,000,000

Loan agreement initiation date

Feb. 25, 2015

Feb. 25, 2015

Principle amount of loan agreement

$ 1,700,000

kr 14,000,000

Accrued interest paid

$ 100,000

kr 650,000

Payable on February 25, 2016 [Member] | S S P Primers Aktieboulag [Member] | Allenex [Member]

Debt Instrument [Line Items]

Loan agreement, periodic payment

$ 500,000

kr 4,000,000

Date of loan agreement payable

Mar. 7, 2016

Mar. 7, 2016

Perceptive Credit Agreement [Member]

Debt Instrument [Line Items]

Aggregate principal amount

$ 15,000,000

Amount of fee paid

$ 300,000

Increase in interest rate in case of default

3.00%

3.00%

Principal outstanding amount

$ 13,337,000

$ 0

Perceptive Credit Agreement [Member] | Tranche A Warrant [Member]

Debt Instrument [Line Items]

Warrant to purchase stock, shares | shares

140,000

Warrant initial exercise price | $ / shares

$ 8.60

Warrant termination date

Apr. 17, 2025

Apr. 17, 2025

Class of warrant exercisable date

Oct. 17, 2018

Oct. 17, 2018

Perceptive Credit Agreement [Member] | Tranche A Warrant [Member] | Common Stock [Member]

Debt Instrument [Line Items]

Class of warrant exercisable date

Apr. 17, 2018

JGB Debt [Member]

Debt Instrument [Line Items]

Unamortized debt discount and issuance costs

$ 6,968,000

Interest rate

9.50%

Debt instrument maturity date

Feb. 28, 2020

Aggregate principal amount

$ 27,780,000

Proceeds from debt, net of issuance costs

24,000,000

Pay-off of term debt

11,200,000

Minimum cash requirement

$ 9,400,000

Debentures convertible into common stock | shares

6,092,105

6,161,331

Conversion price per share | $ / shares

$ 4.33

$ 4.34

$ 4.56

$ 4.40

Debt conversion description

Additionally, after September 1, 2017, upon the satisfaction of certain conditions, including the volume weighted average price of the Company’s common stock exceeding 250% of the Conversion Price for twenty consecutive trading days, the Company could have required that the Debentures be converted into shares of the Company’s common stock, subject to certain limitations.

Minimum required percentage of common stock trading price over conversion price for twenty consecutive trading days to convert debentures into shares

250.00%

Maximum Debt redemption amount per month by each debenture holder after March 1, 2018

$ 937,500

Debt redemption description

Commencing on March 1, 2018, each of the holders of the Debentures had the right, at its option, to require the Company to redeem up to $937,500 of the outstanding principal amount of its Debenture per month. The Company was required to promptly, but in any event no more than one trading day after the holder delivers a redemption notice to the Company, pay the applicable redemption amount in cash or, at the Company’s election and subject to certain conditions, in shares of the Company’s common stock. If the Company elected to pay the redemption amount in shares of the Company’s common stock, then the shares would have been delivered based on a price equal to the lowest of (a) 88% of the average of the three lowest volume weighted average prices of the Company’s common stock over the prior 20 trading days, (b) 88% of the prior trading day’s volume weighted average price, or (c) the Conversion Price.

Considerable maximum average percentage of three lowest volume weighted average prices common stock over the prior 20 trading days for conversion of debt

88.00%

Considerable maximum percentage of prior trading day’s volume weighted average price of common stock for conversion of debt

88.00%

Shares issued upon conversion | shares

1,022,544

1,022,544

6,415,039

6,415,039

Conversion into common stock per share price | $ / shares

$ 1.12

Debentures convertible into common stock, outstanding principal amount

$ 26,700,000

Debentures prepayment date

Apr. 13, 2018

Term loan facility amount outstanding

$ 26,500,000

Amount recognized to additional paid in capital

$ 38,800,000

Extinguishment of unamortized debt discount

2,700,000

Extinguishment of compound derivative liability

12,100,000

Prepayment premium percentage on principal amount

8.00%

Principal outstanding amount

$ 0

14,168,000

JGB Debt [Member] | FastPartner AB [Member] | Allenex [Member]

Debt Instrument [Line Items]

Debt instrument interest rate

8.00%

8.00%

JGB Debt [Member] | Mohammed Al Amoudi [Member] | Allenex [Member]

Debt Instrument [Line Items]

Debt instrument interest rate

6.00%

6.00%

JGB Debt [Member] | Other Income (Expense) [Member]

Debt Instrument [Line Items]

Loss on debt extinguishment

$ 2,800,000

JGB Debt [Member] | Common Stock [Member]

Debt Instrument [Line Items]

Class of warrant exercisable date

Mar. 15, 2017

Debentures convertible into common stock | shares

288,022

Conversion into common stock per share price | $ / shares

$ 4.34

Common stock shares issued | shares

651,240

288,022

6,161,331

Debentures convertible into common stock, outstanding principal amount

$ 1,250,000

$ 6,000

JGB Debt [Member] | If Debentures are Prepaid on or Prior to March 1, 2018 [Member]

Debt Instrument [Line Items]

Prepayment premium percentage on outstanding debt

15.00%

Debt redemption price, percentage

115.00%

JGB Debt [Member] | If the Debentures are Prepaid After March 1, 2018 but Prior to March 1, 2019 [Member]

Debt Instrument [Line Items]

Prepayment premium percentage on outstanding debt

8.00%

Debt redemption price, percentage

108.00%

JGB Debt [Member] | If the Debentures are Prepaid on or After March 1, 2019 [Member]

Debt Instrument [Line Items]

Prepayment premium percentage on outstanding debt

5.00%

Debt redemption price, percentage

105.00%

Subordinated Promissory Note [Member] | FastPartner AB [Member] | Allenex [Member]

Debt Instrument [Line Items]

Interest rate

10.00%

10.00%

10.00%

10.00%

10.00%

10.00%

Debt instrument maturity date

Mar. 31, 2019

Mar. 31, 2019

Aggregate principal amount

$ 500,000

$ 200,000

$ 1,100,000

kr 4,000,000

kr 2,000,000

kr 9,400,000

Repament of outstanding debt

$ 2,500,000

kr 21,300,000

Repayment of accrued interest

200,000

1,600,000

Issuance date

Mar. 7, 2016

Dec. 29, 2015

Jun. 28, 2013

Debt instrument repayment of principal amount outstanding

$ 1,900,000

kr 15,400,000

Debt instrument accrued interest

$ 500,000

Debt instrument interest rate

10.00%

10.00%

Principal outstanding amount

2,400,000

2,400,000

2,400,000

kr 19,757,000

19,757,000

Subordinated Promissory Note [Member] | Mohammed Al Amoudi [Member] | Allenex [Member]

Debt Instrument [Line Items]

Interest rate

10.00%

10.00%

Debt instrument maturity date

Mar. 31, 2019

Mar. 31, 2019

Aggregate principal amount

$ 1,200,000

kr 10,600,000

Repament of outstanding debt

1,900,000

15,700,000

Repayment of accrued interest

100,000

kr 1,200,000

Issuance date

Jun. 28, 2013

Debt instrument repayment of principal amount outstanding

$ 1,300,000

kr 10,600,000

Debt instrument accrued interest

$ 500,000

Debt instrument interest rate

10.00%

10.00%

Principal outstanding amount

1,700,000

1,700,000

1,700,000

14,575,000

kr 14,575,000

Tranche A Term Loan Facility [Member]

Debt Instrument [Line Items]

Aggregate principal amount

15,000,000

Tranche A Term Loan Facility [Member] | Perceptive Credit Agreement [Member]

Debt Instrument [Line Items]

Proceeds from term loan

11,100,000

Tranche A Term Loan and Tranche B Term Loan and Term Loan Facility [Member] | Perceptive Credit Agreement [Member]

Debt Instrument [Line Items]

Aggregate principal amount

$ 10,000,000

Term Loan Facility [Member]

Debt Instrument [Line Items]

Interest rate

9.00%

Interest rate, description

The Term Loan accrues interest per annum at 9.00% (the “Applicable Margin”) plus the greater of the one-month LIBOR or 1.5%.

The Term Loan accrues interest per annum at 9.00% (the “Applicable Margin”) plus the greater of the one-month LIBOR or 1.5%.

Interest rate basis spread

1.50%

1.50%

Debt instrument maturity date

Apr. 17, 2023

Apr. 17, 2023

Term Loan Facility [Member] | Allenex [Member]

Debt Instrument [Line Items]

Term loan facility amount outstanding

$ 5,600,000

kr 47,000,000

Term Loan Facility [Member] | Danske Bank A S [Member]

Debt Instrument [Line Items]

Conditional principal repayment amount

$ 700,000

kr 6,000,000

Term Loan Facility [Member] | Danske Bank A S [Member] | Allenex [Member]

Debt Instrument [Line Items]

Aggregate principal amount

$ 8,800,000

kr 71,000,000

Interest rate, description

The interest rate applicable to each advance was the percentage rate per annum calculated as the aggregate of (i) Stockholm Interbank Offered Rate (“STIBOR”) (as defined in the Term Loan Facility) and (ii) the Margin (as described in the Term Loan Facility) at 3% conditional on the fulfillment of certain criteria.

Interest rate basis spread

3.00%

Loan agreement initiation date

Jun. 25, 2013

Term loan facility available for utilization advances

$ 600,000

5,000,000

Term loan facility integral multiples

$ 100,000

kr 1,000,000

Term Loan Facility [Member] | CareDx International AB [Member]

Debt Instrument [Line Items]

Debt secured assets and pledge equity interests percentage

65.00%

Tranche B Term Loan [Member]

Debt Instrument [Line Items]

Fee payable equal to percentage of principal amount

1.75%

Tranche B Term Loan [Member] | Tranche B Warrant [Member]

Debt Instrument [Line Items]

Warrant to purchase stock, shares | shares

93,333

Warrant initial exercise price | $ / shares

$ 8.60

Tranche B Term Loan [Member] | Perceptive Credit Agreement [Member]

Debt Instrument [Line Items]

Aggregate principal amount

$ 10,000,000

Short Term Credit Facility [Member] | Danske Bank A S [Member] | Allenex [Member]

Debt Instrument [Line Items]

Debt instrument maturity date

Jun. 30, 2018

Aggregate principal amount

$ 1,000,000

$ 1,200,000

kr 10,000,000

kr 8,000,000

Loan agreement initiation date

Jun. 18, 2015

Short term credit facility

$ 500,000

$ 500,000

kr 3,850,000

Danske Term Loan and Credit Facility [Member]

Debt Instrument [Line Items]

Repayment of accrued interest

17,000

kr 142,000

Danske Term Loan and Credit Facility [Member] | Danske Bank A S [Member]

Debt Instrument [Line Items]

Repament of outstanding debt

$ 5,600,000

kr 47,000,000

Accrued and Other Liabilities [Member]

Debt Instrument [Line Items]

Current portion of accrued interest

100,000

Other Liabilities Long Term [Member]

Debt Instrument [Line Items]

Long-term portion of accrued interest

$ 200,000

Debt - Schedule of Future Debt

Debt - Schedule of Future Debt Maturities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Equity Method Investments And Cost Method Investments [Abstract]
2,021	$ 2,025
2,022	2,700
2,023	10,275
Total debt maturities	15,000
Less: debt discount and issuance costs	(1,663)	$ (4,600)
Long-term debt, net of current portion	$ 13,337	$ 18,338

Debt - Carrying Value of Debt o

Debt - Carrying Value of Debt on Issuance Date (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Apr. 17, 2018	Dec. 31, 2017	Mar. 15, 2017
Debt Instrument [Line Items]
Total debt discount	$ (1,663)		$ (4,600)
Perceptive Security Agreement [Member]
Debt Instrument [Line Items]
Debt principal		$ 15,000
Issuance cost		(669)
Discount related to issued warrants		(784)
Embedded derivative liability		(245)
Total debt discount		(1,698)
Carrying value		$ 13,302
JGB Debt [Member]
Debt Instrument [Line Items]
Debt principal				$ 27,780
Issuance cost				(998)
Discount related to issued warrants				(2,780)
Original warrant valuation				(900)
Embedded derivative liability				(2,290)
Total debt discount				(6,968)
Carrying value				$ 20,812

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands	Oct. 10, 2017USD ($)$ / sharesshares	Oct. 05, 2017USD ($)$ / sharesshares	Jun. 30, 2014shares	Jun. 30, 2018shares	Mar. 31, 2018USD ($)$ / sharesshares	Jun. 30, 2018CommercialTestshares	Dec. 31, 2017shares
ImmuMetrix, Inc. [Member] | Contingent Consideration Liability [Member]
Class Of Stock [Line Items]
Issuable common stock under contingent obgligation			227,845				227,845
Number of shares issued pursuant to contingent consideration				227,845		227,845
Milestone description						The shares were issuable upon the Company completing 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020.
Commercial test, measurement and completion date						Jun. 10, 2020
Number of commercial tests involving the measurement of cfDNA to be completed | CommercialTest						2,500
Number of achieved contingent consideration milestone of commercial tests | CommercialTest						2,500
Common Stock [Member] | JGB Debt [Member]
Class Of Stock [Line Items]
Common stock shares issued	651,240	288,022			6,161,331
Common stock offer price per share | $ / shares		$ 4.34			$ 4.33
Conversion of debentures into shares of common stock | $		$ 1,250			$ 26,700
2017 Public Offering [Member]
Class Of Stock [Line Items]
Common stock shares issued	4,992,840
Common stock offer price per share | $ / shares	$ 4
Net proceeds from common stock shares issued at public offering | $	$ 18,300
Over-allotments [Member]
Class Of Stock [Line Items]
Common stock shares issued	651,240

401(K) Plan - Additional Inform

401(K) Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Expense incurred related to plan	$ 0.1	$ 0.1

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Class Of Warrant Or Right [Line Items]
Purchase of common stock warrants exercised		445,000	468,000
Proceeds from exercise of warrants			$ 524	$ 0
Estimated fair value of warrant liability remeasurement income (expense)		$ 5,200	5,400
Maximum [Member]
Class Of Warrant Or Right [Line Items]
Proceeds from exercise of warrants		$ 500	$ 500
ASU 2017-11 [Member] | JGB Debt [Member]
Class Of Warrant Or Right [Line Items]
Warrant to purchase stock, shares	1,338,326
Reclassification of warrant liability to equity	$ 6,600

Warrants - Outstanding Warrants

Warrants - Outstanding Warrants To Purchase Common Stock Warrants (Detail) - Common Stock [Member] - $ / shares		6 Months Ended
		Jun. 30, 2018	Sep. 26, 2016	Sep. 25, 2016
Class Of Warrant Or Right [Line Items]
Number of Shares Underlying Warrants		3,421,422
Class Of Warrant Or Right Issued on August 2009 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date		2009-08
Classified as		Equity
Exercise Price		$ 21.78
Number of Shares Underlying Warrants		33,473
Class Of Warrant Or Right Issued on July 2010 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date		2010-07
Classified as		Equity
Exercise Price		$ 21.78
Number of Shares Underlying Warrants		6,694
Class Of Warrant Or Right Issued on August 2012 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date		2012-08
Classified as		Equity
Exercise Price		$ 21.78
Number of Shares Underlying Warrants		167,182
Class Of Warrant Or Right Issued on January 2015 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date		2015-01
Classified as		Equity
Exercise Price		$ 6.96
Number of Shares Underlying Warrants		34,483
Class Of Warrant Or Right Issued on March 2017 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[1]	2017-03
Classified as	[1]	Equity
Exercise Price	[1]	$ 4.67
Number of Shares Underlying Warrants	[1]	1,338,326
Tranche A Term Loan Facility [Member] | Class Of Warrant Or Right Issued on April 2018 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[2]	2018-04
Classified as	[2]	Equity
Exercise Price	[2]	$ 8.60
Number of Shares Underlying Warrants	[2]	140,000
Tranche B Term Loan [Member] | Class Of Warrant Or Right Issued on April 2018 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[3]	2018-04
Classified as	[3]	Equity
Exercise Price	[3]	$ 8.60
Number of Shares Underlying Warrants	[3]	93,333
Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on August 2009 [Member]
Class Of Warrant Or Right [Line Items]
Original Term		10 years
Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on July 2010 [Member]
Class Of Warrant Or Right [Line Items]
Original Term		9 years
Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on August 2012 [Member]
Class Of Warrant Or Right [Line Items]
Original Term		7 years
Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on January 2015 [Member]
Class Of Warrant Or Right [Line Items]
Original Term		5 years
Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on March 2017 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[1]	5 years
Remaining Term (in Years) [Member] | Tranche A Term Loan Facility [Member] | Class Of Warrant Or Right Issued on April 2018 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[2]	7 years
Remaining Term (in Years) [Member] | Tranche B Term Loan [Member] | Class Of Warrant Or Right Issued on April 2018 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[3]	7 years
Private Placement [Member] | Accredited Investors [Member]
Class Of Warrant Or Right [Line Items]
Exercise Price			$ 4	$ 4.98
Private Placement [Member] | Accredited Investors [Member] | Class Of Warrant Or Right Issued on April 2016 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[4]	2016-04
Classified as	[4]	Liability
Exercise Price	[4]	$ 1.12
Number of Shares Underlying Warrants	[4]	469,124
Private Placement [Member] | Accredited Investors [Member] | Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on April 2016 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[4]	7 years
Private Placement [Member] | Placement Agents [Member] | Class Of Warrant Or Right Issued on April 2016 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[5]	2016-04
Classified as	[5]	Liability
Exercise Price	[5]	$ 1.12
Number of Shares Underlying Warrants	[5]	136,300
Private Placement [Member] | Placement Agents [Member] | Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on April 2016 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[5]	5 years
Subsequent Financing [Member] | Class Of Warrant Or Right Issued on June 2016 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	[6]	2016-06
Classified as	[6]	Liability
Exercise Price	[6]	$ 4
Number of Shares Underlying Warrants	[6]	1,002,507
Subsequent Financing [Member] | Remaining Term (in Years) [Member] | Class Of Warrant Or Right Issued on June 2016 [Member]
Class Of Warrant Or Right [Line Items]
Original Term	[6]	7 years
[1]	Issued on March 15, 2017 in connection with the JGB Debt. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the number of shares issuable pursuant to the JGB Warrants increased from 1,250,000 to 1,296,679 and the exercise price of the JGB Warrants was adjusted from $5.00 to $4.82, effective July 3, 2017. As a result of the 2017 Public Offering, effective October 5, 2017, the aggregate number of shares of common stock issuable upon exercise of the JGB Warrants increased from 1,296,679 to 1,338,326 shares and the exercise price of the JGB Warrants decreased from $4.82 to $4.67 per share.
[2]	Issued on April 17, 2018 in connection with the Perceptive Credit Agreement.
[3]	The Perceptive Credit Agreement included a Tranche B loan amount available at the Company’s option at any time from April 17, 2018 to April 17, 2019. If the Tranche B Term Loan is funded, the Company will issue Perceptive a Tranche B Warrant to purchase up to 93,333 shares of common stock an exercise price of $8.60. The Perceptive Tranche B Warrant is considered issued for accounting purposes only and will not be exercisable unless and until legally issued in connection with a funding of the Tranche B Term Loan.
[4]	Issued on April 14, 2016 in connection with the private placement to certain accredited investors. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with such private placement was adjusted from $4.98 to $4.00, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $4.00 to $1.12, effective July 3, 2017.
[5]	Issued on April 14, 2016 in connection with the private placement to placement agents. As a result of the issuance of 1,022,544 shares of the Company’s common stock at $1.12 in connection with the amendments to the Conditional Share Purchase Agreement, the exercise price was adjusted from $3.99 to $1.12, effective July 3, 2017.
[6]	Issued on June 15, 2016 in connection with a subsequent private placement. In accordance with the anti-dilution provisions, the exercise price of the warrants issued in connection with the subsequent private placement was adjusted from $4.98 per share to $4.00 per share, which was the price paid by investors in the Company’s underwritten public offering of common stock, which closed on September 26, 2016. The exercise price remained at $4.00 as the anti-dilution provision was waived for the issuance of shares related to the July 3, 2017 amendment to the Conditional Share Purchase Agreements.

Warrants - Outstanding Warran66

Warrants - Outstanding Warrants To Purchase Common Stock Warrants (Parenthetical) (Detail) - $ / shares

Apr. 17, 2018

Jul. 01, 2017

Mar. 31, 2018

Jun. 30, 2018

Dec. 31, 2017

Apr. 17, 2019

Oct. 10, 2017

Jul. 03, 2017

Jul. 02, 2017

Mar. 15, 2017

Sep. 26, 2016

Sep. 25, 2016

JGB Debt [Member]

Class Of Warrant Or Right [Line Items]

Shares issued upon conversion

1,022,544

6,415,039

6,415,039

Perceptive Credit Agreement [Member] | Tranche A Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Oct. 17, 2018

Exercise Price

$ 8.60

Warrant to purchase stock, shares

140,000

Common Stock [Member]

Class Of Warrant Or Right [Line Items]

Warrants issued

3,421,422

Common Stock [Member] | JGB Debt [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Mar. 15, 2017

Common Stock [Member] | Perceptive Credit Agreement [Member] | Tranche A Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Apr. 17, 2018

Common Stock [Member] | Perceptive Credit Agreement [Member] | Tranche B Warrant [Member] | Subsequent Event [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

$ 8.60

Common Stock [Member] | Perceptive Credit Agreement [Member] | Tranche B Warrant [Member] | Maximum [Member] | Subsequent Event [Member]

Class Of Warrant Or Right [Line Items]

Warrant to purchase stock, shares

93,333

Common Stock [Member] | Private Placement [Member] | Accredited Investors [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Apr. 14, 2016

Exercise Price

$ 4

$ 4.98

Common Stock [Member] | Private Placement [Member] | Placement Agents [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Apr. 14, 2016

Common Stock [Member] | Subsequent Financing [Member]

Class Of Warrant Or Right [Line Items]

Warrants, issued date

Jun. 15, 2016

Common Stock [Member] | Conditional Share Purchase Agreement [Member] | JGB Debt [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

$ 1.12

$ 5

Shares issued upon conversion

1,022,544

Warrants issued

1,250,000

Common Stock [Member] | Conditional Share Purchase Agreement [Member] | Accredited Investors [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

1.12

$ 4

Shares issued upon conversion

1,022,544

Common Stock [Member] | Conditional Share Purchase Agreement [Member] | Placement Agents [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

1.12

$ 3.99

Shares issued upon conversion

1,022,544

Common Stock [Member] | Conditional Share Purchase Agreement [Member] | Former Majority Shareholders [Member] | JGB Debt [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

$ 4.82

Warrants issued

1,296,679

Common Stock [Member] | Subsequent Private Placement [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

$ 4

$ 4.98

Common Stock [Member] | 2017 Public Offering [Member] | JGB Debt [Member]

Class Of Warrant Or Right [Line Items]

Exercise Price

$ 4.67

$ 4.82

Warrants issued

1,296,679

1,338,326

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Option, Unvested RSU Activity under 2014 Equity Incentive Plan and 2016 Inducement Plan and Related Information (Detail)	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	156,429
Shares Available for Grant, Additional options authorized	1,957,075
Shares Available for Grant, RSUs forfeited	13,050
Shares Available for Grant, RSUs vested	0
Shares Available for Grant, Repurchases of common stock under employee incentive plans	67,656
Shares Available for Grant, Options granted	(809,634)
Shares Available for Grant, Options exercised	0
Shares Available for Grant, Options forfeited	20,453
Shares Available for Grant, Options expired	1,817
Shares Available for Grant, Ending Balance	674,093
Number of Shares, Beginning Balance	1,941,473
Number of Shares, Additional options authorized	0
Number of Shares, Options granted	809,634
Number of Shares, Options exercised	(167,379)
Number of Shares, Options forfeited	(20,453)
Number of Shares, Options expired	(1,817)
Number of Shares, Ending Balance	2,561,458
Weighted-Average Exercise Price, Beginning Balance | $ / shares	$ 4.21
Weighted-Average Exercise Price, Additional options authorized | $ / shares	0
Weighted-Average Exercise Price, Options granted | $ / shares	11.05
Weighted-Average Exercise Price, Options exercised | $ / shares	1.07
Weighted-Average Exercise Price, Options forfeited | $ / shares	4.78
Weighted-Average Exercise Price, Options expired | $ / shares	3.55
Weighted-Average Exercise Price, Ending Balance | $ / shares	$ 6.57
Number of RSU Shares, forfeited	(13,050)
Restricted Stock Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant	17,919
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant	714,834
Shares Available for Grant, RSUs forfeited	13,050
Shares Available for Grant, RSUs vested	(244,806)
Number of RSU Shares, Beginning Balance	439,926
Number of RSU Shares, forfeited	(13,050)
Number of RSU Shares, Ending Balance	896,904
Weighted Average Grant- Date Fair Value, Unvested beginning balance | $ / shares	$ 4.39
Weighted- Average Grant Date Fair Value, RSUs granted | $ / shares	11.63
Weighted- Average Grant Date Fair Value, RSUs forfeited | $ / shares	4.87
Weighted- Average Grant Date Fair Value, RSUs vested | $ / shares	9.30
Weighted Average Grant- Date Fair Value, Unvested ending balance | $ / shares	$ 8.83

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 900,000
Share-based compensation expense, tax benefit recognized	0
Share-based compensation expense, capitalized	0
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate proceeds from the issuance of shares	$ 300,000	$ 100,000
Shares issued under ESPP	42,534	34,176
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of RSUs	$ 3,000,000
Total unrecognized compensation costs related to stock options and RSUs	$ 6,600,000
Stock options and RSUs expected weighted average period	3 years 4 months 13 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs related to stock options and RSUs	$ 5,800,000
Stock options and RSUs expected weighted average period	3 years 3 months 29 days
Intrinsic value of options	$ 13,600,000

Stock Incentive Plans - Summa69

Stock Incentive Plans - Summary of Options Outstanding Vested and Expected to Vest (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Vested | shares	991,627
Number of Shares, Expected to vest | shares	1,360,609
Number of Shares, Total | shares	2,352,236
Weighted-average Exercise Price, Vested | $ / shares	$ 6.57
Weighted-average Exercise Price, Expected to vest | $ / shares	$ 7.83
Weighted-average Remaining Contractual Life (Years), Vested	6 years 8 months 23 days
Weighted-average Remaining Contractual Life (Years), Expected to vest	7 years 6 months 14 days
Aggregate Intrinsic Value, Vested | $	$ 7,400
Aggregate Intrinsic Value, Expected to vest | $	6,191
Aggregate Intrinsic Value, Total | $	$ 13,591

Stock Incentive Plans - Weighte

Stock Incentive Plans - Weighted-Average Assumptions Used to Estimated Fair Value of Share-Based Awards (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Shares of common stock subject to outstanding options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years	6 years	6 years	6 years
Expected volatility	66.00%		68.75%
Expected volatility, minimum		55.46%		53.07%
Expected volatility, maximum		57.71%		57.71%
Risk-free interest rate	2.76%		2.71%
Risk-free interest rate, minimum		1.90%		1.90%
Risk-free interest rate, maximum		1.96%		2.12%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months	6 months
Expected volatility	105.32%	62.27%	105.32%	62.27%
Risk-free interest rate	1.61%	0.65%	1.61%	0.65%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Stock Incentive Plans - Summa71

Stock Incentive Plans - Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	$ 2,512	$ 495	$ 3,217	$ 886
Cost of testing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	191	63	252	119
Research and Development Expense [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	462	111	675	175
Sales and marketing expense [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	466	57	529	95
General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	$ 1,393	$ 264	$ 1,761	$ 497

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018
Income Taxes Disclosure [Line Items]
Benefit for income taxes	$ 381	$ 376	$ 805	$ 659
Scenario Plan [Member]
Income Taxes Disclosure [Line Items]
GILTI tax rate					10.50%

Segment Reporting - Additional

Segment Reporting - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)Segment	Jun. 30, 2017USD ($)
Segment Reporting [Abstract]
Number of reportable segments | Segment			2
Intersegment sales | $	$ 0	$ 0	$ 0	$ 0

Segment Reporting - Operating R

Segment Reporting - Operating Results of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 17,823	$ 12,046	$ 31,876	$ 23,630
Operating loss	(5,209)	(3,599)	(10,444)	(12,143)
Depreciation and amortization	986	887	2,025	1,821
Total assets	79,879		79,879		$ 83,565
Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	14,171	8,670	24,917	16,587
Operating loss	(3,138)	(2,662)	(6,333)	(8,121)
Depreciation and amortization	316	236	645	498
Total assets	48,851		48,851		48,734
Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	3,652	3,376	6,959	7,043
Operating loss	(2,071)	(937)	(4,111)	(4,022)
Depreciation and amortization	670	$ 651	1,380	$ 1,323
Total assets	$ 31,028		$ 31,028		$ 34,831

Segment Reporting - Reportable

Segment Reporting - Reportable Revenues by Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 17,823	$ 12,046	$ 31,876	$ 23,630
Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	14,171	8,670	24,917	16,587
Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	3,652	3,376	6,959	7,043
North America [Member] | Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	14,147	8,647	24,876	16,549
North America [Member] | Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	1,489	983	2,418	1,983
Europe [Member] | Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	24	23	41	38
Europe [Member] | Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	1,856	1,863	3,829	3,922
Australia [Member] | Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Australia [Member] | Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	31	125	105	241
Rest of The World [Member] | Post-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Rest of The World [Member] | Pre-Transplant [Member]
Segment Reporting Information [Line Items]
Revenues	$ 276	$ 405	$ 607	$ 897

Segment Reporting - Long-Lived

Segment Reporting - Long-Lived Assets Consisting of Property and Equipment, Net by Geographic Regions (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Long-lived assets	$ 2,360	$ 2,075
North America [Member]
Segment Reporting Information [Line Items]
Long-lived assets	1,572	1,206
Europe [Member]
Segment Reporting Information [Line Items]
Long-lived assets	708	776
Australia [Member]
Segment Reporting Information [Line Items]
Long-lived assets	$ 80	$ 93