Commitments and Contingencies Disclosure [Abstract] Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Headquarters and laboratory facilities, South San Francisco, lease signed April 2015 Headquarters And Laboratory Facilities South San Francisco Lease Two [Member] Represents the lease for headquarters and laboratory space in South San Francisco, California that expires March 2026. Laboratory facilities, Austin, Texas Laboratory Facilities Austin Texas [Member] Represents the lease for laboratory facilities in Austin, Texas that expires July 2018. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other assets Other Noncurrent Assets [Member] Operating Leases Operating Leased Assets [Line Items] Amount of space leased (in square feet) Lessee Leasing Arrangements, Operating Leases, Space Leased Amount of space leased under the terms of the agreement. Security deposit Security Deposit Future minimum lease payments under non-cancelable operating leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Remainder of 2018 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease payments Operating Leases, Future Minimum Payments Due Facilities rent expense Operating Leases, Rent Expense, Net Payables and Accruals [Abstract] Schedule of accrued liabilities Schedule of Accrued Liabilities [Table Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of credit Line of Credit [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Future principal payments Long-term Debt, Fiscal Year Maturity [Abstract] 2019 Long-term Debt, Maturities, Repayments of Principal in Year Two 2020 Long-term Debt, Maturities, Repayments of Principal in Year Three 2021 Long-term Debt, Maturities, Repayments of Principal in Year Four 2022 Long-term Debt, Maturities, Repayments of Principal in Year Five Total Long-term Debt, Gross Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net loss Net Income (Loss) Available to Common Stockholders, Basic Adjustments to reconcile net loss to net cash used in operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Stock-based compensation Share-based Compensation Other income Tax Benefit from Legal Settlement Tax Benefit from Legal Settlement Amortization of debt issuance costs Amortization of Debt Issuance Costs and Discounts Interest on end-of-term debt obligation Interest Expense and Prepayment Penalty Interest Expense and Prepayment Penalty Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Supplies Increase (Decrease) in Inventories Prepaid expenses and current other assets Increase (Decrease) in Prepaid Expense and Other Assets Other assets Increase (Decrease) in Other Noncurrent Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued liabilities and deferred rent Increase (Decrease) in Accrued Liabilities and Deferred Rent The increase (decrease) during the reporting period in the amount of expenses incurred but not yet paid and deferred rent. Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sale of property and equipment Proceeds from Sale of Property, Plant, and Equipment Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from the issuance of common stock in a public offering, net of costs Proceeds from Issuance of Common Stock Proceeds from legal settlement regarding short-swing profits Proceeds from Legal Settlements Payment of capital lease liability Repayments of Long-term Capital Lease Obligations Proceeds from the exercise of common stock options and employee stock purchases Proceeds from Stock Options Exercised Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplementary cash flow information of non-cash investing and financing activities: Supplemental Cash Flow Information [Abstract] Total cash, cash equivalents and restricted cash Purchases of property and equipment included in accounts payable and accrued liabilities Capital Expenditures Incurred But Not Yet Paid Net Future cash outflow (inflow) to pay for purchases of fixed assets that have occurred. Interest paid on debt Interest Paid, Excluding Capitalized Interest, Operating Activities Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents, Noncurrent Statement of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Accounts receivable Accounts Receivable, Net, Current Supplies Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property and equipment, net Property, Plant and Equipment, Net Finite-lived intangible assets, net Finite-Lived Intangible Assets, Net Goodwill Goodwill Other assets Other Assets, Noncurrent Total assets Assets Liabilities and Stockholders’ Equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued liabilities Accrued Liabilities, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Capital lease liability, net of current portion Capital Lease Obligations Deferred rent, net of current portion Deferred Rent Credit, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.001 par value; 5,000,000 shares authorized, no shares issued and outstanding as of September 30, 2018 and December 31, 2017 Preferred Stock, Value, Issued Common stock, $0.001 par value; 125,000,000 shares authorized, 40,535,674 and 34,210,388 shares issued and outstanding as of September 30, 2018 and December 31, 2017, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated deficit Retained Earnings (Accumulated Deficit) Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Accounting Policies [Abstract] Schedule of Cash and Cash Equivalents [Table] Schedule of Cash and Cash Equivalents [Table] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] Over-Allotment Option Over-Allotment Option [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Tissue Samples Product [Member] Other Services Service [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Accrued Income Receivable Accrued Income Receivable [Member] Cash and Cash Equivalents [Line Items] Cash and Cash Equivalents [Line Items] Number of operating segments Number of Operating Segments Number of products Number of Products Number of Products Number of shares issued and sold (in shares) Stock Issued During Period, Shares, New Issues Price per share (in usd per share) Sale of Stock, Price Per Share Stock issuance costs Payments of Stock Issuance Costs Number of major financial institutions with which the company's cash and cash equivalents are deposited Number of Major Financial Institutions with which Cash and Cash Equivalents Deposited Represents the number of major financial institutions, with which cash and cash equivalents are deposited by the entity. Long term deposit consisting of letter of credit serving as security for lease Revenue recognized received in cash Revenue Recognized Received In Cash Revenue recognized during the period based on cash receipts. Revenue Revenues Loss from operations Operating Income (Loss) Net income (loss) per common share, basic and diluted (in usd per share) Earnings Per Share, Basic and Diluted Contract with customer, revenue recognized Contract with Customer, Liability, Revenue Recognized Revenue, remaining performance obligation Revenue, Remaining Performance Obligation, Amount Performance obligation, amount to be recognized per quarter Revenue, Remaining Performance Obligation, Amount, Per Quarter Revenue, Remaining Performance Obligation, Amount, Per Quarter Contract agreement term Term, Contract Agreement Term, Contract Agreement Automatic renewal period of contract agreement Automatic Renewal Period, Contract Agreement Automatic Renewal Period, Contract Agreement Litigation settlement, amount awarded from other party Litigation Settlement, Amount Awarded from Other Party Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Concentrations of Credit Risk and Other Risks and Uncertainties Concentrations of Credit and Other Risks and Uncertainties [Policy Text Block] Disclosure of accounting policy for concentrations of credit risk and other risks and uncertainties. Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Preferred stock, par value (in usd per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, issued (in shares) Preferred Stock, Shares Issued Preferred stock, outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (in usd per share) Common Stock, Par or Stated Value Per Share Common stock, authorized (in shares) Common Stock, Shares Authorized Common stock, issued (in shares) Common Stock, Shares, Issued Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Income Tax Disclosure [Abstract] Unrecognized tax benefit Unrecognized Tax Benefits Interest expense or penalties related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Equity [Abstract] Schedule of reserved shares of common stock for issuance Schedule of Common Stock Capital Shares Reserved for Future Issuance [Table Text Block] Tabular disclosure of number of common shares reserved for future issuance. Earnings Per Share [Abstract] Schedule of outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Income Statement [Abstract] Operating expenses: Operating Expenses [Abstract] Cost of revenue Cost of Revenue Research and development Research and Development Expense Selling and marketing Selling and Marketing Expense General and administrative General and Administrative Expense Intangible asset amortization Amortization of Intangible Assets Total operating expenses Costs and Expenses Loss from operations Interest expense Interest Expense Other income, net Other Nonoperating Income (Expense) Net loss Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net loss per common share, basic and diluted (in usd per share) Shares used to compute net loss per common share, basic and diluted (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Net Loss Per Common Share Earnings Per Share [Text Block] Debt principal Debt Instrument, Face Amount End-of-term debt obligation Debt instrument end of term payment interest amount Represents the amount of interest end of term payment of debt. Unamortized debt issuance costs Debt Instrument, Unamortized Discount Net debt obligation Long-term Debt Organization and Description of Business Business Description and Basis of Presentation [Text Block] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Revenue concentration risk Customer Concentration Risk [Member] Gross receivables concentration risk Credit Concentration Risk [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Revenue Sales Revenue Gross [Member] Revenue from sale of goods and services rendered, in the normal course of business, before deducting sales returns and allowances, and sales discounts, when it serves as a benchmark in a concentration of risk calculation. Accounts receivable Accounts Receivable [Member] Concentration Risk Concentration Risk [Line Items] Schedule of the Company's third-party payers as a percentage of total Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Schedule of Capital Leased Assets [Table] Schedule of Capital Leased Assets [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Equipment Equipment [Member] Capital Leased Assets [Line Items] Capital Leased Assets [Line Items] Capital leased equipment Capital Leased Assets, Gross Upfront payment Capital Lease, Upfront Payment Capital Lease, Upfront Payment Present value of future minimum payments Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments Payment for remainder of 2018 Capital Leases, Future Minimum Payments, Remainder of Fiscal Year Payment for 2019 Capital Leases, Future Minimum Payments Due in Two Years Accrued compensation expenses Employee-related Liabilities, Current Accrued other Other Accrued Liabilities, Current Total accrued liabilities Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Initial term loan Initial Term Loan [Member] Represents the initial term loan. Debt Prepayment Tranche [Axis] Debt Prepayment Tranche [Axis] Debt Prepayment Tranche [Axis] Debt Payment Tranche [Domain] Debt Payment Tranche [Domain] [Domain] for Debt Payment Tranche [Axis] Debt prepayment tranche one Debt Prepayment Tranche One [Member] Debt Prepayment Tranche One [Member] Debt prepayment tranche two Debt Prepayment Tranche Two [Member] Debt Prepayment Tranche Two [Member] Debt prepayment tranche three Debt Prepayment Tranche Three [Member] Debt Prepayment Tranche Three [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Secured debt Secured Debt [Member] Revolving credit facility Revolving Credit Facility [Member] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Silicon Valley Bank Silicon Valley Bank [Member] Silicon Valley Bank [Member] Visium Visium [Member] Represents information pertaining to Visium Healthcare Partners, LP Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Effective interest rate (as a percent) Debt Instrument, Interest Rate, Effective Percentage Prepayment premium Debt Instrument, Prepayment Premium Amount of prepayment premium waived. Balloon payment to be paid Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid Liquidity requirement, minimum Liquidity Requirement, Minimum Liquidity Requirement, Minimum Number of term loans Number Of Term Loans Represents the number of term loans available to the Company. Proceeds from lines of credit Proceeds from Lines of Credit Repayments of long-term debt Repayments of Long-term Debt Payment of end of term obligation Payment of End of Term Obligation The cash outflow for the payment of the end-of-term obligation and prepayment penalty. Document and Entity Information Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Ex Transition Period Entity Ex Transition Period Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Shares of common stock subject to outstanding options (in shares) Employee And Non Employee Stock Option [Member] An arrangement whereby an employee or non-employee is entitled to receive in the future, subject to vesting and other restrictions, number of shares in the entity at a specified price, as defined in the agreement. ESPP (in shares) Employee Stock [Member] Class of Stock [Line Items] Class of Stock [Line Items] Common Stock Common Stock [Abstract] No definition available. Options issued and outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Shares available for issuance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Total number of shares reserved for issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Thyroid Cytopathology Partners Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Thyroid Cytopathology Partners Variable Interest Entity, Not Primary Beneficiary [Member] Thyroid Cytopathology Partners Variable Interest Entity [Line Items] Notice of intent not to renew period Agreement Terms, Non-Renewal Notice Period Represents the minimum period required to provide notice of intent not to renew agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Contract termination fee Contract Termination Fee Contract Termination Fee Payment installments for contract termination fee (in installments) Payment Installments for Contract Termination Fee Payment Installments for Contract Termination Fee Expenses for cytopathology testing and evaluation services Testing and Evaluation Services Expense Testing and evaluation service costs directly related to generating revenues. Outstanding obligations Reduction to rent expense for TCP's portion of costs for subleased space Other Income Rent Reimbursement Amount of reimbursement from third party for rent and related operating expenses for shared space included in other income in the income statement. Schedule of debt obligation for borrowings Schedule of Debt [Table Text Block] Schedule of debt obligation payments Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Employee stock purchase plan (in shares) Employee Stock Option [Member] Restricted stock units (in shares) Restricted Stock Units (RSUs) [Member] Outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Total common stock equivalents (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Debt Debt Disclosure [Text Block] Schedule of future minimum lease payments under non-cancelable operating leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Medicare Medicare [Member] Represents information pertaining to Medicare, a significant third-party payer. UnitedHealthcare United Healthcare [Member] Represents information pertaining to United Healthcare, a significant third-party payer. Concentrations of Credit Risk and Other Risks and Uncertainties Concentrations of credit risk (as a percent) Concentration Risk, Percentage Thyroid Cytopathology Partners Long-term Contracts or Programs Disclosure [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value, Measurements, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level I Fair Value, Inputs, Level 1 [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Money market funds Money Market Funds [Member] Fair value measurements Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Financial assets Assets, Fair Value Disclosure Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]