Fair Value Disclosures [Abstract] Changes in fair value of redeemable convertible preferred stock warrants Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Change in fair value recorded in other (income) expense, net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Conversion of preferred stock warrants to common stock warrants Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Ending balance Earnings Per Share [Abstract] Schedule of Basic and Diluted Net Loss per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Other Liabilities Disclosure [Abstract] Class of Warrant or Right [Table] Class of Warrant or Right [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Class A [Member] Redeemable Convertible Preferred Stock Redeemable Preferred Stock [Member] Series 5 Preferred Stock Series E Preferred Stock [Member] Series 6 Preferred Stock Series F Preferred Stock [Member] Series 7 Preferred Stock Series G Preferred Stock [Member] Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Warrants Issued 7/1/2012 Warrants Issued July First Twenty Twelve [Member] Warrants Issued July First Twenty Twelve [Member] Warrants Issued 7/19/2013 Warrants Issued July Nineteenth Twenty Thirteen [Member] Warrants Issued July Nineteenth Twenty Thirteen [Member] Warrants Issued 11/26/2014 Warrants Issued November 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Warrants or Rights Price per Share (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Fair Value Warrants Outstanding, Fair Value On Date Of Issuance Or Conversion Warrants Outstanding, Fair Value On Date Of Issuance Or Conversion Warrants exercise period from date of issuance Warrants and Rights Outstanding, Term Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Stockholders’ Notes Receivable Receivables from Stockholder [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Accumulated Deficit Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Temporary Equity Increase (Decrease) in Temporary Equity [Roll Forward] Temporary equity, beginning 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(Decrease) in Stockholders' Equity [Roll Forward] Stockholders' equity (deficit), beginning balance (shares) Shares, Outstanding Stockholders' equity (deficit), beginning balance Stockholders' Equity Attributable to Parent Issuance of common stock upon exercise of stock options (shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Issuance of common stock upon exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Issuance of common stock upon exercise of unvested stock options (shares) Stock Issued During Period, Shares, Unvested Stock Options Exercised Stock Issued During Period, Shares, Unvested Stock Options Exercised Issuance of common stock upon exercise of unvested stock options Stock Issued During Period, Value, Unvested Stock Options Exercised Stock Issued During Period, Value, Unvested Stock Options Exercised Conversion from preferred stock to common stock (shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Conversion from preferred stock to common stock Stock Issued During Period, Value, Conversion of Convertible Securities Conversion from preferred stock warrants to common stock warrants Adjustments to Additional Paid in Capital, Warrant Converted Adjustments to Additional Paid in Capital, Warrant Converted Issuance of common stock from warrants exercise (shares) Stock Issued During Period, Shares, Warrants Exercised Stock Issued During Period, Shares, Warrants Exercised Issuance of common stock from warrants exercise Stock Issued During Period, Value, Warrants Exercised Stock Issued During Period, Value, Warrants Exercised Issuance of common stock from IPO Proceeds, net (shares) Stock Issued During Period, Shares, New Issues Issuance of common stock from IPO Proceeds, net Stock Issued During Period, Value, New Issues Repurchase of unvested early exercised stock options (shares) Stock Repurchased During Period, Originally Issued For Exercise 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Of Capital Stock, Forgiveness Of Debt Vesting of early exercised stock options Adjustments to Additional Paid in Capital, Share-based Compensation, Vesting Of Early Exercised Stock Options Adjustments to Additional Paid in Capital, Share-based Compensation, Vesting Of Early Exercised Stock Options Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Unrealized gain of marketable securities Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Net loss Net Income (Loss) Attributable to Parent Stockholders' equity (deficit), ending balance (shares) Stockholders' equity (deficit), ending balance Organization, Consolidation and Presentation of Financial Statements [Abstract] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] IPO IPO [Member] Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] Reverse stock split ratio Stockholders' Equity Note, Stock Split, Conversion Ratio Number of shares issued in IPO (in shares) Sale of Stock, Number of Shares Issued in Transaction IPO share price (in dollars per share) Sale of Stock, Price Per Share Net proceeds from IPO Sale of Stock, Consideration Received on Transaction Common stock issued upon conversion of redeemable convertible preferred stock (in shares) Number of warrants converted (in shares) Class Of Warrant Or Right, Number Of Warrants Or Rights Converted Class of Warrant or Right, Number of Warrants or Rights Converted Warrants to purchase shares of stock (in shares) Adjustments to additional paid-in capital related to warrants Adjustments to Additional Paid in Capital, Warrant Issued Investments, Debt and Equity Securities [Abstract] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] CURRENT ASSETS Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Debt Securities, Available-for-sale Accounts receivable, net of allowance for doubtful accounts of $263 and $268 at December 31, 2018 and 2017, respectively Accounts Receivable, Net, Current Inventory 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 Other non-current assets Other Assets, Noncurrent TOTAL ASSETS Assets LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) Liabilities and Equity [Abstract] CURRENT LIABILITIES Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued liabilities and other Accrued Liabilities, Current Total current liabilities Liabilities, Current Redeemable convertible preferred stock warrants Preferred Stock Warrant Liability Preferred Stock Warrant Liability Long-term borrowings Long-term Debt, Excluding Current Maturities Other long-term liabilities Other Liabilities, Noncurrent TOTAL LIABILITIES Liabilities Commitments and contingencies Commitments and Contingencies Redeemable convertible preferred stock, $0.0001 par value; Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests [Abstract] Redeemable convertible preferred stock; Authorized: 0 and 12,104,749 shares at December 30, 2018 and December 31, 2017; issued and outstanding: 0 and 11,871,578 shares at December 30, 2018 and December 31, 2017; (Liquidation preference of $0 and $119,194 at December 30, 2018 and December 31, 2017). STOCKHOLDERS’ EQUITY (DEFICIT) Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.0001 par value; Authorized: 5,000,000 and 0 shares at December 31, 2018 and 2017, respectively; no shares issued and outstanding as of December 31, 2018 and 2017. Preferred Stock, Value, Issued Common stock, $0.0001 par value; Authorized: 100,000,000 and 19,333,333 shares at December 31, 2018 and 2017, respectively; issued and outstanding: 24,450,757 and 3,603,140 shares, at December 31, 2018 and 2017, respectively. Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) TOTAL STOCKHOLDERS’ EQUITY (DEFICIT) TOTAL LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) Liabilities and Equity Accounting Policies [Abstract] Warranty term (in years) Standard Product Warranty Term Standard Product Warranty Term Sales credit reserve term (in years) Sales Credit Reserve Period Sales Credit Reserve Period Fair Value Measurement Fair Value Disclosures [Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [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] Machinery and equipment Machinery and Equipment [Member] Construction in progress Construction in Progress [Member] Computer and office equipment Computer And Office Equipment [Member] Computer And Office Equipment [Member] Leasehold improvements Leasehold Improvements [Member] Furniture and fixtures Furniture and Fixtures [Member] Property and Equipment, Net Property, Plant and Equipment [Line Items] Property and equipment, gross Property, Plant and Equipment, Gross Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property and equipment, net Depreciation expense Depreciation Commitments and Contingencies Disclosure [Abstract] Schedule of Aggregate Future Minimum Lease Payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Offering costs capitalized Deferred Offering Costs Offering costs transferred to additional paid-in capital Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Offering costs expensed Offering Costs Expensed 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[Member] Pharmakon Term Loan Pharmakon Term Loan [Member] Pharmakon Term Loan [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate Prime Rate [Member] Debt, Prepayment Penalty, Period [Axis] Debt, Prepayment Penalty, Period [Axis] Debt, Prepayment Penalty, Period [Axis] Debt, Prepayment Penalty, Period [Domain] Debt, Prepayment Penalty, Period [Domain] [Domain] for Debt, Prepayment Penalty, Period [Axis] Prepayment Penalty, 31-48 Months Prepayment Penalty, 31-48 Months [Member] Prepayment Penalty, 31-48 Months [Member] Prepayment Penalty, 49-60 Months Prepayment Penalty, 49-60 Months [Member] Prepayment Penalty, 49-60 Months [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Long term borrowings Long-term Debt Debt face amount Debt Instrument, Face Amount Debt period payment, interest only period Debt Instrument, Periodic Payment, Interest Only Period Debt Instrument, Periodic Payment, Interest Only Period Debt 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(expense), net Other Nonoperating Income (Expense) Net loss Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized gain of marketable securities Changes in foreign currency translation Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net loss per share, basic and diluted (in dollars per share) Earnings Per Share, Basic and Diluted Weighted-average number of common shares used to compute basic and diluted net loss per share (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Impairment losses on long-lived assets Impairment of Long-Lived Assets Held-for-use Effective Income Tax Rate Reconciliation Effective Income Tax Rate Reconciliation, Percent [Abstract] Tax at statutory federal rate (percent) Effective Income Tax Rate Reconciliation, at 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Contract Early termination fees Gain (Loss) on Contract Termination Rent expense Operating Leases, Rent Expense, Net Purchase commitments related to inventory Purchase Obligation Costs to defend lawsuits or settle claims Litigation Settlement, Expense Costs accrued to defend lawsuits Estimated Litigation Liability Temporary Equity, by Class of Stock [Table] Temporary Equity, by Class of Stock [Table] Series 1 Preferred Stock Series A Preferred Stock [Member] Series 2 Preferred Stock Series B Preferred Stock [Member] Series 3 Preferred Stock Series C Preferred Stock [Member] Series 4 Preferred Stock Series D Preferred Stock [Member] Temporary Equity [Line Items] Temporary Equity [Line Items] Shares Authorized (in shares) Temporary Equity, Shares Authorized Redeemable convertible preferred stock issued (in shares) Temporary Equity, Shares Issued Redeemable convertible preferred stock outstanding (in shares) Carrying Value Liquidation Value Temporary Equity, Liquidation Preference 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share (in dollars per share) Temporary Equity, Liquidation Preference Per Share Liquidation participation cap per share (in dollars per share) Temporary Equity, Liquidation Participation Cap Per Share Temporary Equity, Liquidation Participation Cap Per Share Conversion price (in dollars per share) Convertible Preferred Stock, Conversion Price Convertible Preferred Stock, Conversion Price Conversion ratio (in shares) Convertible Preferred Stock, Shares Issued upon Conversion Minimum public offering for conversion Convertible Preferred Stock, Minimum Public Offering For Conversion Convertible Preferred Stock, Minimum Public Offering For Conversion Minimum public offering per share for conversion (in dollars per share) Convertible Preferred Stock, Minimum Public Offering Per Share For Conversion Convertible Preferred Stock, Minimum Public Offering Per Share For Conversion Net Loss Per Share of Common Stock Earnings Per Share [Text Block] Range [Axis] Range [Axis] Range [Domain] Range 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Weighted-average remaining contractual life, options vested and expected to vest (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value, options vested and exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Aggregate intrinsic value, options vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Stock-Based Incentive Compensation Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Current tax expense: Current Income Tax Expense (Benefit), Continuing Operations 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Items] Quarterly increase in revenue target (percent) Revenue Target, Quarterly Increase, Percentage Revenue Target, Quarterly Increase, Percentage Restricted Stock Units Restricted Stock Units (RSUs) [Member] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Unvested, ending balance 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Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Purchase price of common stock as a percent of fair market value (percent) Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Employees stock purchase program offering period interval (in months) Share-Based Compensation Arrangement By Share-Based Payment Award, Offering Period Interval Share-Based Compensation Arrangement By Share-Based Payment Award, Offering Period Interval Early exercise of stock options, share subject to repurchase (in shares) Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Early Exercise, Common Stock Subject To Repurchase Share-based Compensation Arrangement by Share-based Payment Award, Options, Early Exercise, Common Stock Subject To Repurchase Liability for early exercise of unvested stock options Liability For Early Exercise Of Options, Current Liability For Early 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Total marketable securities, Unrealized Gains Marketable Securities, Accumulated Gross Unrealized Gain, Before Tax Marketable Securities, Accumulated Gross Unrealized Gain, Before Tax Total marketable securities, Unrealized Losses Marketable Securities, Accumulated Gross Unrealized Loss, Before Tax Marketable Securities, Accumulated Gross Unrealized Loss, Before Tax Total marketable securities, Aggregate Fair Value Marketable Securities, Fair Value Total aggregate fair value for marketable securities included in cash equivalents and investments. Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Change in allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Recoveries Stock-based compensation Share-based Compensation Change in fair value of redeemable convertible preferred stock warrants Fair Value Adjustment of Warrants Loss on write-off of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Write-off of debt discount Write-Off Of Debt Discount Write off of Debt Discount Write-off of public offering costs Write Off Of Initial Public Offering Costs Write off of Initial Public Offering Costs Forgiveness of notes receivable Debt Instrument, Decrease, Forgiveness Short-term investments accretion Accretion (Amortization) of Discounts and Premiums, Investments Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Inventory Increase (Decrease) in Inventories Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued liabilities and other Increase (Decrease) in Accrued Liabilities Net cash used in operating activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Purchase of short-term investments Payments to Acquire Marketable Securities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from initial public offering, net of underwriting discounts and commissions Proceeds from Issuance Initial Public Offering Proceeds from the exercise of common stock options, net Proceeds from Stock Options Exercised Repurchase of common stock Payments for Repurchase of Common Stock Repayment of debt financing Extinguishment of debt financing Proceeds from debt financing Proceeds from Issuance of Long-term Debt Payment of debt issuance costs Payments of Debt Issuance Costs Proceeds from the issuance of redeemable convertible preferred stock, net Proceeds from Issuance of Redeemable Preferred Stock Payments of public offering costs Payments of Stock Issuance Costs Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net decrease in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at Cash and Cash Equivalents [Abstract] Beginning of period End of period Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Supplemental disclosure of non-cash information Noncash Investing and Financing Items [Abstract] Conversion of redeemable convertible preferred stock to common stock Conversion of Stock, Amount Converted Conversion of preferred stock warrants to common stock warrants Net Exercise of Common Warrants Net Exercise of Common Warrants Vesting of early exercised stock options Vesting Of Early Exercised Stock Options Vesting of Early Exercised Stock Options Purchases of property and equipment included in accounts payable and accrued liabilities Capital Expenditures Incurred but Not yet Paid Public offering costs included in accounts payable and accrued liabilities Initial Public Offering Costs Incurred But Not Yet Paid Initial Public Offering Costs Incurred But Not Yet Paid Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Redeemable convertible preferred stock, par value (in dollars per share) Temporary Equity, Par or Stated Value Per Share Redeemable convertible preferred stock authorized (in shares) Redeemable convertible preferred stock, liquidation preference Preferred stock, par value (in dollars 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 dollars 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 Schedule of Antidilutive 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