Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Accrued compensation and related expenses for employee payroll deductions Other Employee-related Liabilities, Current Pay vs Performance Disclosure [Line Items] Schedule of Accrued Liabilities and Other Schedule of Accrued Liabilities [Table Text Block] Accrued liabilities and other Accrued liabilities and other Outstanding liability Accrued Liabilities, Current Statistical Measurement [Domain] Statistical Measurement [Domain] Revolving credit facility, aggregate principal amount Line of Credit Facility, Maximum Borrowing Capacity Research and development Research and Development Expense Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Related Party Transaction [Line Items] Related Party Transaction [Line Items] Accrued royalty Accrued Royalties, Current Equity Award [Domain] Award Type [Domain] Fair Value as of Grant Date Award Grant Date Fair Value Outstanding, beginning of period (in shares) Outstanding, end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Borrowings Debt Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Revolving Credit Facility Revolving Credit Facility [Member] Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Performance Shares Performance Shares [Member] Accounts payable Accounts Payable, Current Restatement Determination Date: Restatement Determination Date [Axis] Corporate bonds Corporate bonds Corporate Debt Securities [Member] Accrued interest receivable Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss Commitments and contingencies (Note 6) Commitments and Contingencies Insider Trading Policies and Procedures [Line Items] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Proceeds from public offering, net of discounts and commissions Proceeds from Issuance of Common Stock Accrued Liabilities and Other Accrued Liabilities, Current [Abstract] Issuance of common stock upon exercise of warrant, net of shares withheld (in shares) Stock Issued During Period, Exercise Of Warrants, Shares Stock Issued During Period, Exercise Of Warrants, Shares Geographical [Axis] Geographical [Axis] Proceeds from issuance of common stock under employee stock purchase plan Proceeds from Stock Plans Income Taxes Income Tax Disclosure [Text Block] Dividend yield (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Current liabilities: Liabilities, Current [Abstract] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, $0.0001 par value; 5,000,000 shares authorized; no shares issued and outstanding Preferred Stock, Value, Issued Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Canceled and forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price ESPP purchase rights Employee Stock Purchase Plan Shares [Member] Employee Stock Purchase Plan Shares [Member] Net loss per share, diluted (in usd per share) Earnings Per Share, Diluted Class of Warrant or Right [Line Items] Class of Warrant or Right [Line Items] PEO Total Compensation Amount PEO Total Compensation Amount Construction in progress, surgical placement instrument set Construction in Progress, Surgical Placement Instrument Set [Member] Construction in Progress, Surgical Placement Instrument Set Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Accounts receivable, net of allowance for credit losses of $500 and $400, respectively Accounts Receivable, after Allowance for Credit Loss, Current Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Line of Credit Line of Credit [Member] Outstanding, beginning of period (in shares) Outstanding, end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Liability associated with indemnifications Estimated Litigation Liability Aggregate Fair Value Debt Securities, Available-for-Sale, Excluding Accrued Interest Issuance of common stock upon exercise of stock options, net of shares withheld Stock Issued During Period, Value, Stock Options Exercised Trading Symbol Trading Symbol U.S. agency bonds US Government Agencies Debt Securities [Member] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Marketable securities Investments, Fair Value Disclosure Net loss Net loss Net Income (Loss) Total current liabilities Liabilities, Current Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Company Selected Measure Name Company Selected Measure Name Machinery and equipment Machinery and Equipment [Member] LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Employee Stock Employee Stock [Member] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] STOCKHOLDERS’ EQUITY Equity, Attributable to Parent [Abstract] Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Issuance of common stock upon exercise of stock options, net of shares withheld (in shares) Additional shares purchased after exercise of option (in shares) Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Warrant Exercised Warrant Exercised [Member] Warrant Exercised Schedule of Computation of Basic and Diluted Net Loss per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Cost of goods sold Cost of Goods and Services Sold Performance period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Executive Category: Executive Category [Axis] Warrants Issued 12/22/2016 Warrants Issued December Twenty-Second Twenty Sixteen [Member] Warrants Issued December Twenty-Second Twenty Sixteen [Member] Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Other Commitments [Table] Other Commitments [Table] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Exercised (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Level 1 Fair Value, Inputs, Level 1 [Member] Name Measure Name Name Forgone Recovery, Individual Name Schedule of Property and Equipment, Net Property, Plant and Equipment [Table Text Block] Equity Components [Axis] Equity Components [Axis] Price per Share (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Financial Instruments [Domain] Financial Instruments [Domain] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Accrued liabilities and other Increase (Decrease) in Accrued Liabilities 2025 Long-Term Debt, Maturity, Year Two Stock options granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Underlying Securities Award Underlying Securities Amount Entity Small Business Entity Small Business Local Phone Number Local Phone Number Accounts receivable Increase (Decrease) in Accounts Receivable Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Remainder of 2023 Long-Term Debt, Maturity, Remainder of Fiscal Year Measurement Frequency [Axis] Measurement Frequency [Axis] Operating lease liabilities, net of current portion Operating Lease, Liability, Noncurrent Restricted Stock Units Restricted stock units Restricted Stock Units (RSUs) [Member] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Class of Warrant or Right [Table] Class of Warrant or Right [Table] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Depreciation expense Depreciation Schedule of Marketable Securities Marketable Securities [Table Text Block] Payments of debt issuance costs Payments of Debt Issuance Costs Income Statement Location [Axis] Income Statement Location [Axis] Schedule of Outstanding Borrowings Schedule of Long-Term Debt Instruments [Table Text Block] Expected volatility of peer companies, minimum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Peer Companies, Minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Peer Companies, Minimum Schedule of Future Minimum Lease Payments Under Non-Cancelable Operating Leases Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Number of shares offered by a selling stockholder (in shares) Sale of Stock, Number of Shares Issued in Transaction Schedule of Anti-dilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Other Performance Measure, Amount Other Performance Measure, Amount Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Summary of Information Related to Lease Expense and Valuation of Lease Assets and Lease Liabilities Lease, Cost [Table Text Block] Inventory Increase (Decrease) in Inventories Unrealized gain (loss) on marketable securities Net unrealized gain (loss) on marketable securities Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Research and development Research and Development Expense [Member] Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Common stock equivalents excluded from computation of diluted net loss per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Award Type [Axis] Award Type [Axis] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Plan Name [Domain] Plan Name [Domain] Document Quarterly Report Document Quarterly Report Warrants Issued 3/1/2017 Warrants Issued March First Twenty Seventeen [Member] Warrants Issued March First Twenty Seventeen [Member] Supplemental disclosure of non-cash information Noncash Investing and Financing Items [Abstract] Interest expense Interest Expense Unrecognized compensation cost Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Unpaid purchases of property and equipment Capital Expenditures Incurred but Not yet Paid Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] General and administrative General and Administrative Expense [Member] Property and equipment, gross Property, Plant and Equipment, Gross Final fee as percentage of aggregate principal amount (percent) Debt Instrument, Fee Amount As Percentage Of Aggregate Principal Debt Instrument, Fee Amount As Percentage Of Aggregate Principal Leased assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Trading Arrangement: Trading Arrangement [Axis] Related Party Transaction Related Party Transactions Disclosure [Text Block] Less: imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Use of Estimates Use of Estimates, Policy [Policy Text Block] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Entity File Number Entity File Number Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Restricted Stock Unit Activity Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Operating lease liabilities, current portion Operating Lease, Liability, Current 2026 Long-Term Debt, Maturity, Year Three Unpaid public offering costs Public Offering Costs, Payable Public Offering Costs, Payable Issuance of common stock related to employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Entity Shell Company Entity Shell Company 2026 Lessee, Operating Lease, Liability, to be Paid, Year Three Risk-free interest rate, minimum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Property, Plant and Equipment [Line Items] Property and Equipment, Net Property, Plant and Equipment [Line Items] Recently Adopted Accounting Standards and Recent Accounting Standards Not Yet Effective New Accounting Pronouncements, Policy [Policy Text Block] Restatement Determination Date Restatement Determination Date Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Beginning of period End of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents 2025 Lessee, Operating Lease, Liability, to be Paid, Year Two Public offering price (in dollars per share) Sale of Stock, Price Per Share Interest income Investment Income, Interest Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Variable lease expense Variable Lease, Cost Operating lease expense Operating Lease, Cost Common stock issued (in shares) Common Stock, Shares, Issued Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Gross profit Gross Profit Accordion feature, increase limit Line of Credit Facility, Accordion Feature, Increase Limit Line of Credit Facility, Accordion Feature, Increase Limit Security Exchange Name Security Exchange Name Outstanding debt, net of debt issuance costs and unaccreted value of final fee Long-Term Debt 2027 Long-Term Debt, Maturity, Year Four Contingent fee, amount Line of Credit Facility, Contingent Commitment Fee, Amount Line of Credit Facility, Contingent Commitment Fee, Amount Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Warrants Issued 11/9/2015 Warrants Issued November Ninth Twenty Fifteen [Member] Warrants Issued November Ninth Twenty Fifteen [Member] Stock Options Stock options Employee Stock Option [Member] Construction in Progress, Santa Clara Lease Construction in Progress, Santa Clara Lease [Member] Construction in Progress, Santa Clara Lease Aggregate Future Minimum Lease Payments Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Common Stock Common Class A [Member] Unrecognized compensation cost, expected period for recognition (in years) Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Maximum Maximum [Member] Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Carrying value Cash Equivalents, at Carrying Value Document Type Document Type Tabular List, Table Tabular List [Table Text Block] Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Operating lease liabilities that had not commenced. Lessee, Operating Lease, Lease Not Yet Commenced, Liability Lessee, Operating Lease, Lease Not Yet Commenced, Liability Stock-Based Incentive Compensation Plans Share-Based Payment Arrangement [Text Block] SVB Amended Term Loan SVB Amended Term Loan [Member] SVB Amended Term Loan Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Weighted-Average Exercise Price Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Proceeds from (repayments of) term loan Proceeds from (Repayments of) Secured Debt Allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Income Statement [Abstract] Income Statement [Abstract] Issuance of common stock from public offerings, net of underwriting discounts, commissions and offering costs (in shares) Stock Issued During Period, Shares, New Issues Title of 12(b) Security Title of 12(b) Security Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Short-term investments Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Related Party [Domain] Related Party, Type [Domain] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Outstanding, beginning of period (in dollars per share) Outstanding, end of period (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Income Tax Disclosure [Abstract] Income Tax Disclosure [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] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Future principal and final fee payments Maturities of Long-Term Debt [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-Based Payment Arrangement [Abstract] Entity Tax Identification Number Entity Tax Identification Number Inventory Inventory, Net Total lease expense Lease, Cost Purchases of marketable securities Payments to Acquire Marketable Securities Number of purchase periods in offering interval Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Purchase Periods Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Purchase Periods Statistical Measurement [Axis] Statistical Measurement [Axis] Financial Instrument [Axis] Financial Instrument [Axis] Entity Interactive Data Current Entity Interactive Data Current Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] 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] Total Shareholder Return Amount Total Shareholder Return Amount Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Surgical equipment and instrument trays Surgical Equipment and Instrument Trays [Member] Surgical Equipment and Instrument Trays Accumulated deficit Retained Earnings (Accumulated Deficit) Measure: Measure [Axis] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Name Outstanding Recovery, Individual Name Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Aggregate principal amount Debt Instrument, Face Amount Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Current assets: Assets, Current [Abstract] Other Commitments [Line Items] Other Commitments [Line Items] Entity Address, State or Province Entity Address, State or Province Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Cash paid for amounts included in the measurement of operating lease liabilities Operating Lease, Payments Common stock outstanding (in shares) Stockholders' equity, beginning of period (in shares) Stockholders' equity, end of period (in shares) Common Stock, Shares, Outstanding Indemnification Agreement Indemnification Agreement [Member] Warrants Issued 7/22/2013 Warrants Issued July Twenty-Second Twenty Thirteen [Member] Warrants Issued July Twenty-Second Twenty Thirteen [Member] Interest and other income (expense), net: Other Income and Expenses [Abstract] PEO PEO [Member] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Changes in foreign currency translation Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Class of Stock [Domain] Class of Stock [Domain] Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Debt Instrument [Axis] Debt Instrument [Axis] Costs to defend lawsuits or settle claims Litigation Settlement, Expense Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Total operating lease liabilities Operating Lease, Liability Credit Facility [Axis] Credit Facility [Axis] Warrants Issued 11/26/2014 Warrants Issued November Twenty-Sixth Twenty Fourteen [Member] Warrants Issued November Twenty-Sixth Twenty Fourteen [Member] Schedule of Future Principal and Final Fee Payments Schedule of Maturities of Long-Term Debt [Table Text Block] TOTAL LIABILITIES Liabilities Schedule of Stock-Based Compensation Share-Based Payment Arrangement, Activity [Table Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accumulated Other Comprehensive Income AOCI Attributable to Parent [Member] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Total marketable securities, Aggregate Fair Value Cash, Cash Equivalents, and Short-Term Investments Fair Value, Measurement Frequency [Domain] Measurement Frequency [Domain] All Executive Categories All Executive Categories [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Plan Name [Axis] Plan Name [Axis] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Sales and marketing Selling and Marketing Expense Common stock, $0.0001 par value; 100,000,000 shares authorized; 40,087,765 and 34,731,577 shares issued and outstanding, respectively Common Stock, Value, Issued General and administrative General and Administrative Expense Credit losses on investments Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Accrued professional services Accrued Professional Fees, Current Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Segments Segment Reporting, Policy [Policy Text Block] Total current assets Assets, Current Correlation coefficient of peer companies, minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient Of Peer Companies, Minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient Of Peer Companies, Minimum All Individuals All Individuals [Member] Other income (expense), net Other Nonoperating Income (Expense) Entity Filer Category Entity Filer Category Purchase commitments related to inventory management and training materials Purchase Obligation Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Statement [Table] Statement [Table] Current Fiscal Year End Date Current Fiscal Year End Date PEO Name PEO Name Expected volatility of common stock, minimum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Warrants outstanding, beginning balance (in shares) Warrants outstanding, ending balance (in shares) Class of Warrant or Right, Outstanding Preferred stock authorized (in shares) Preferred Stock, Shares Authorized Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Preferred stock outstanding (in shares) Preferred Stock, Shares Outstanding Marketable Securities [Line Items] Marketable Securities [Line Items] Employee ESPP contributions Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Excluding Option Exercised Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Class of Stock [Axis] Class of Stock [Axis] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Others Other Accrued Liabilities, Current Unaccreted value of final fee Debt Instrument, Fee Amount Thereafter Lessee, Operating Lease, Liability, to be Paid, After Year Four Lessee, Operating Lease, Liability, to be Paid, After Year Four The Company and Nature of Business Nature of Operations [Text Block] Depreciation and amortization Depreciation, Depletion and Amortization Adjusted quick ratio threshold Debt Instrument, Covenant, Adjusted Quick Ratio, Minimum Debt Instrument, Covenant, Adjusted Quick Ratio, Minimum Furniture and fixtures Furniture and Fixtures [Member] Fixed interest rate (percent) Debt Instrument, Interest Rate, Stated Percentage Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] TOTAL STOCKHOLDERS’ EQUITY Stockholders' equity, beginning of period Stockholders' equity, end of period Equity, Attributable to Parent Commercial paper Commercial paper Commercial Paper [Member] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Total commitment fee, amount Line of Credit Facility, Commitment Fee Amount Maturities of marketable securities Proceeds From Maturity Of Marketable Securities Proceeds From Maturity Of Marketable Securities Warrants Issued 10/20/2015 Warrants Issued October Twentieth Twenty Fifteen [Member] Warrants Issued October Twentieth Twenty Fifteen [Member] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Preferred stock issued (in shares) Preferred Stock, Shares Issued Level 2 Fair Value, Inputs, Level 2 [Member] Black-Scholes option-pricing model assumptions Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract] Contingent interest rate increase due to default Debt Instrument, Interest Rate Increase Due to Default Debt Instrument, Interest Rate Increase Due to Default Entity Emerging Growth Company Entity Emerging Growth Company Less: Unamortized debt issuance costs Debt Issuance Costs, Net Inventory, finished goods, gross Inventory, Finished Goods, Gross Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Short-term investments Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current Document Fiscal Period Focus Document Fiscal Period Focus 2024 Lessee, Operating Lease, Liability, to be Paid, Year One Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Antidilutive Securities [Axis] Antidilutive Securities [Axis] 2027 Lessee, Operating Lease, Liability, to be Paid, Year Four Title Trading Arrangement, Individual Title Outstanding, beginning of period (in dollars per share) Outstanding, end of period (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Stock-based compensation Share-Based Payment Arrangement, Noncash Expense SVB Term Loan SVB Term Loan [Member] SVB Term Loan Schedule of Revenue by Geography Revenue from External Customers by Geographic Areas [Table Text Block] Common Stock Common Stock [Member] Individual: Individual [Axis] City Area Code City Area Code Entity Address, Postal Zip Code Entity Address, Postal Zip Code Net Loss Per Share of Common Stock Earnings Per Share [Text Block] Income Statement Location [Domain] Income Statement Location [Domain] Employee 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 Document Fiscal Year Focus Document Fiscal Year Focus Marketable Securities [Table] Marketable Securities [Table] Geographical [Domain] Geographical [Domain] 2018 ESPP 2018 Employee Stock Purchase Plan [Member] A2018 Employee Stock Purchase Plan [Member] Computer and office equipment Computer And Office Equipment [Member] Computer And Office Equipment [Member] Accrued interest writeoff Debt Securities, Available-for-Sale, Accrued Interest Writeoff Minimum Minimum [Member] Property and equipment, net Property and equipment, net Property, Plant and Equipment, Net Schedule of Stock Option Activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] Exercise Price Award Exercise Price Schedule of Warrants Issued and Outstanding Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] ASSETS Assets [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] First-Citizens Term Loan First-Citizens Term Loan [Member] First-Citizens Term Loan Proceeds from debt financing Proceeds from Issuance of Long-Term Debt U.S. treasury securities U.S. treasury securities US Treasury Securities [Member] Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Accumulated Deficit Retained Earnings [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Accretion (amortization) of discount and premium on marketable securities Accretion (Amortization) of Discounts and Premiums, Investments TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity Other non-current assets Other Assets, Noncurrent Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Net loss per share, basic (in usd per share) Earnings Per Share, Basic Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Cash and cash equivalents at Cash equivalents Cash Equivalents, at Carrying Value [Abstract] Issuance of common stock related to employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Accounting Policies [Abstract] Accounting Policies [Abstract] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Risk-free interest rate, maximum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Expected volatility of common stock, maximum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Remainder of 2023 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Arrangement Duration Trading Arrangement Duration Entity Address, City or Town Entity Address, City or Town Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Related Party Related Party [Member] Principles of Consolidation Consolidation, Policy [Policy Text Block] Correlation coefficient of peer companies, maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient Of Peer Companies, Maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient Of Peer Companies, Maximum Balance Sheet Components Supplemental Balance Sheet Disclosures [Text Block] Total marketable securities, Amortized Cost Marketable Securities, Amortized Cost Total amortized cost for marketable securities included in cash equivalents and investments. Document Transition Report Document Transition Report Award Timing Predetermined Award Timing Predetermined [Flag] Termination Date Trading Arrangement Termination Date Accounts payable Increase (Decrease) in Accounts Payable Common stock authorized (in shares) Common Stock, Shares Authorized Warrants Exercised (in shares) Class of Warrant or Right, Shares, Exercised Class of Warrant or Right, Shares, Exercised Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Principal outstanding and final fee Total principal and final fee payments Long-Term Debt, Gross Related Party Transactions [Abstract] Related Party Transactions [Abstract] All Trading Arrangements All Trading Arrangements [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Award Timing Disclosures [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Royalties Royalty Expense Accounts receivable credit losses Provision Accounts Receivable, Credit Loss Expense (Reversal) Additional paid-in capital Additional Paid in Capital Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Canceled and forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Proceeds from the exercise of stock options Proceeds from Stock Options Exercised Term of product royalty sales period (in years) Related Party Transaction, Term Of Agreement Related Party Transaction, Term Of Agreement Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Inventory, work in process, gross Inventory, Work in Process, Gross Canceled and forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Insider Trading Arrangements [Line Items] Balance at beginning of period Balance at end of period Accounts Receivable, Allowance for Credit Loss 2024 Long-Term Debt, Maturity, Year One Related Party [Axis] Related Party, Type [Axis] Entity Registrant Name Entity Registrant Name Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Award Timing Method Award Timing Method [Text Block] Schedule of Share-based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions Schedule of Share-based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions Adjustment to Compensation, Amount Adjustment to Compensation Amount Cost of goods sold Cost of Sales [Member] Document Period End Date Document Period End Date Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Adoption Date Trading Arrangement Adoption Date Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Schedule of Marketable Securities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Issuance of common stock upon vesting of restricted stock units (in shares) Stock Issued During Period Shares Restricted Stock Units Stock Issued During Period Shares Restricted Stock Units Repayments of debt financing Repayments of Long-Term Debt Schedule of Accounts Receivable and Allowance for Credit Losses Accounts Receivable, Allowance for Credit Loss [Table Text Block] Entity Central Index Key Entity Central Index Key Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Loss on disposal of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Stock-based compensation expense Share-Based Payment Arrangement, Expense Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income tax provision Income Tax Expense (Benefit) Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] International Non-US [Member] Write-offs Accounts Receivable, Allowance for Credit Loss, Writeoff Accrued compensation and related expenses Employee-related Liabilities, Current Fair Value Measurement Fair Value Disclosures [Text Block] Name Trading Arrangement, Individual Name Number of business activities Number Of Business Activities Number Of Business Activities Issuance of common stock upon vesting of restricted stock units Stock Issued During Period, Value, New Issues Weighted average remaining lease term (in years) Operating Lease, Weighted Average Remaining Lease Term Revenue Revenue from Contract with Customer, Excluding Assessed Tax Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Amendment Flag Amendment Flag Money market funds Money market funds Money Market Funds [Member] Schedule of Performance-based Restricted Stock Unit Activity Arrangement Share-Based Payment Arrangement, Performance Shares, Activity [Table Text Block] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Shares issued under ESPP (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period Marketable securities Assets, Fair Value Disclosure [Abstract] Credit Facility [Domain] Credit Facility [Domain] Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Long-term borrowings Long-Term Debt, Excluding Current Maturities Leasehold improvements Leasehold Improvements [Member] Sales and marketing Selling and Marketing Expense [Member] Weighted-average number of common shares used to compute diluted net loss per share (in shares) Weighted Average Number of Shares Outstanding, Diluted Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Common stock warrants Common Stock Warrants [Member] Common Stock Warrants [Member] Operating expenses: Operating Expenses [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Company Selected Measure Amount Company Selected Measure Amount Additional Paid-in Capital Additional Paid-in Capital [Member] TOTAL ASSETS Assets Name Awards Close in Time to MNPI Disclosures, Individual Name Cover [Abstract] Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Amortization of debt issuance costs Amortization of Debt Issuance Costs United States UNITED STATES Recurring Fair Value, Recurring [Member] Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Warrants Issued (in shares) Class of Warrant or Right, Shares, Issued Class of Warrant or Right, Shares, Issued Expected volatility of peer companies, maximum (percent) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Peer Companies, Maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Peer Companies, Maximum Effective interest rate during the period (percent) Debt Instrument, Interest Rate During Period Other long-term liabilities Other Liabilities, Noncurrent Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Non-NEOs Non-NEOs [Member] Canceled and forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period Total operating lease payments Lessee, Operating Lease, Liability, to be Paid Construction in progress Construction in Progress [Member] Reimbursement charges expensed Reimbursement Charges, Expensed Reimbursement Charges, Expensed Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] Total operating expenses Operating Expenses Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Accounts receivable borrowing base (percent) Debt Instrument, Accounts Receivable Borrowing Base Debt Instrument, Accounts Receivable Borrowing Base Term loan Secured Debt [Member] Non-PEO NEO Non-PEO NEO [Member] Equity Component [Domain] Equity Component [Domain] Adjustment to Compensation: Adjustment to Compensation [Axis] 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 Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Debt Instrument [Line Items] Debt Instrument [Line Items] Weighted-average number of common shares used to compute basic net loss per share (in shares) Weighted Average Number of Shares Outstanding, Basic Entity Current Reporting Status Entity Current Reporting Status Loss from operations Operating Income (Loss) Warrants Expired (in shares) Class of Warrant or Right, Shares, Expired Class of Warrant or Right, Shares, Expired Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Statement [Line Items] Statement [Line Items] Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table]