Organization and Description of Business (Policies)	9 Months Ended
Organization and Description of Business (Policies)	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. The condensed balance sheet as of September 30, 2017, the condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2017 and 2016, and the condensed statements of cash flows for the nine months ended September 30, 2017 and 2016 are unaudited, but include all adjustments, consisting only of normal recurring adjustments, which the Company considers necessary for a fair presentation of its financial position, operating results and cash flows for the periods presented. The condensed balance sheet at December 31, 2016 has been derived from audited financial statements. The results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results expected for the full year or any other period. The accompanying interim period condensed financial statements and related financial information included in this Quarterly Report on Form 10-Q should be read in conjunction with the audited financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.
Use of Estimates	Use of Estimates The preparation of unaudited interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Significant items subject to such estimates include: revenue recognition; contractual allowances; the useful lives of property and equipment; the recoverability of long-lived assets; the estimation of the fair value of intangible assets; stock options; income tax uncertainties, including a valuation allowance for deferred tax assets; and contingencies. The Company bases these estimates on historical and anticipated results, trends and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenue and expenses that are not readily apparent from other sources. Actual results could differ from those estimates and assumptions.
Concentrations of Credit Risk and Other Risks and Uncertainties	Concentrations of Credit Risk and Other Risks and Uncertainties The majority of the Company’s cash and cash equivalents are deposited with one major financial institution in the United States. Deposits in this institution may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses on its deposits of cash and cash equivalents. Several of the components of the Company’s sample collection kit and test reagents are obtained from single-source suppliers. If these single-source suppliers fail to satisfy the Company’s requirements on a timely basis, it could suffer delays in being able to deliver its diagnostic solutions, a possible loss of revenue, or incur higher costs, any of which could adversely affect its operating results. The Company is also subject to credit risk from its accounts receivable related to its sales. The Company generally does not perform evaluations of customers’ financial condition and generally does not require collateral.
Restricted Cash	Restricted Cash The Company had deposits of $120,000 included in current assets as of December 31, 2016, pledged for corporate credit cards and there was no such restricted amounts as of September 30, 2017. The Company also had deposits of $603,000 included in long-term assets as of September 30, 2017 and December 31, 2016, restricted from withdrawal and held by a bank in the form of collateral for an irrevocable standby letter of credit held as security for the lease of the Company’s South San Francisco facility.
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with the provision of ASC 954-605, Health Care Entities — Revenue Recognition ("ASC 954").
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. The Company will adopt the new revenue standard as of January 1, 2018 using the modified retrospective method. The Company has completed its assessment of the five steps of this ASU and believes that the adoption of this ASU will not result in a material cumulative catch-up adjustment under the modified retrospective method, or have a material impact on the Company's financial position or results of operations. In February 2016, the FASB issued ASU No. 2016-2, Leases. This ASU is aimed at making leasing activities more transparent and comparable, and requires substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The ASU will be effective for interim and annual periods beginning after December 15, 2018. Entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited and early adoption is permitted. The Company is currently evaluating the potential effect of this standard on its financial statements. In March 2016, the FASB issued ASU 2016-9, Compensation - Stock Compensation, related to the tax effects of share-based awards. The ASU requires that all the tax effects of share-based awards be recorded through the income statement, thereby simplifying the current guidance that requires excess tax benefits and certain excess tax deficiencies to be recorded in equity. This ASU also permits an election for the impact of forfeitures on the recognition of expense for share-based payment awards where forfeitures can be estimated or recognized when they occur. This ASU is effective for interim and annual periods beginning after December 15, 2016. The Company adopted this ASU as of January 1, 2017 and elected to continue using its forfeiture estimation method for share-based payment awards. This ASU was adopted prospectively and the impact of adoption on the Company's financial statements was not material. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows - Restricted Cash. This ASU requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The ASU will be effective for interim and annual periods beginning after December 15, 2017. The Company does not anticipate that the adoption of this ASU will have a significant impact on its financial statements.