Commitments and Contingencies Disclosure [Abstract] Number of legal proceedings, regulatory matters, or other, disputes or claims Number Of Legal Proceedings Regulatory Matters Or Other Disputes Or Claims Number of legal proceedings, regulatory matters, or other, disputes or claims. Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components Equity Components [Axis] Equity Component Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [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 Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance Stockholders' Equity Attributable to Parent Beginning balance (shares) Shares, Outstanding Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Exercise of stock options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercise of common stock warrants Stock Issued During Period Value Common Stock Warrants Exercised Stock issued during period value common stock warrants exercised. Exercise of common stock warrants (shares) Stock Issued During Period Shares Common Stock Warrants Exercised Stock issued during period shares common stock warrants exercised. Issuance of common stock for Employee Stock Purchase Plan Stock Issued During Period, Value, Employee Stock Purchase Plan Issuance of common stock for Employee Stock Purchase Plan (shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Fair value of common stock warrants at time of exercise Fair Value Of Common Stock Warrants At Time Of Exercise Fair value of common stock warrants at time of exercise. Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Foreign currency translation gain (loss) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Unrealized gain (loss) on short-term investments Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Net loss Net Income (Loss) Attributable to Parent Adjustment to retained earnings from adoption of ASC 606 Cumulative Effect on Retained Earnings, Net of Tax Issuance of common stock in public offering, net of underwriter’s discount and offering costs Issuance Of Common Stock Initial Public Offering Net Of Underwriting Discounts And Commissions Issuance of common stock initial public offering net of underwriting discounts and commissions. Issuance of common stock in public offering, net of underwriter’s discount and offering costs (shares) Issuance Of Common Stock Initial Public Offering Net Of Underwriting Discounts And Commissions Shares Issuance of common stock initial public offering net of underwriting discounts and commissions shares. Share-based compensation (shares) Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Ending balance Ending balance (shares) Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Antidilutive Securities Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities, Name [Domain] Shares underlying outstanding warrants Warrant [Member] Shares underlying outstanding stock options Stock Options Issued And Outstanding [Member] Stock options issued and outstanding. Shares authorized for future equity award grants Grant [Member] Shares authorized for issuance pursuant to awards granted under the ESPP Stock Compensation Plan [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Common stock reserved for future issuance Common Stock, Capital Shares Reserved for Future Issuance Investments, Debt and Equity Securities [Abstract] Short-Term Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Leases [Abstract] 2019 (remaining) Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total future minimum lease payments Lessee, Operating Lease, Liability, Payments, Due Less: amount representing interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Present value of future minimum lease payments Operating Lease, Liability Less: current portion of operating lease liabilities Operating Lease, Liability, Current Operating lease liabilities - long-term Operating Lease, Liability, Noncurrent Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type Long-term Debt, Type [Axis] Long-term Debt, Type Long-term Debt, Type [Domain] Term Loan Agreement Term Loan [Member] Term loan. Term Loan Amendments Term Loan Amendments [Member] Term loan amendments. Debt Instrument [Line Items] Debt Instrument [Line Items] Loan outstanding Long-term Debt Accrued interest Interest Payable Associated financing fees Financial Services Liabilities Interest rate Debt Instrument, Interest Rate, Stated Percentage Interest payable as cash Interest Rate Interest rate. Compounded interest payable Compounded Interest Rate Compounded interest rate. Interest-only payments description Debt Instrument, Payment Terms Maturity date for interest-only payment Debt Instrument Date Of Last Required Interest Payment Debt instrument date of last required interest payment. Warrants issue to purchase common stock Class of Warrant or Right, Number of Securities Called by Warrants or Rights Contractual life (years) Class Of Warrant Or Rights Outstanding Contractual Life Class of warrant or rights outstanding contractual life. Outstanding warrants Class of Warrant or Right, Outstanding Warrants exercise price (USD per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Organization and basis of presentation. Product and Service Product and Service [Axis] Product and Service Product and Service [Domain] Insulin Pump Insulin Pump [Member] Insulin pump. T:slim X2 T Slim X2 [Member] T:slim X2. Range Range [Axis] Range Range [Domain] Minimum Minimum [Member] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Organization and basis of presentation. Expected life span term Product Life Span Term Product life span term. Percentage of new pump shipments represented by product hardware platform Percentage Of New Pump Shipments Represented By Product Hardware Platform Percentage of new pump shipments represented by product hardware platform. Cash and cash equivalents and short-term investments Cash, Cash Equivalents, and Short-term Investments Accumulated deficit Retained Earnings (Accumulated Deficit) Class of Warrant or Right Class of Warrant or Right [Axis] Class of Warrant or Right Class of Warrant or Right [Domain] Series A warrants Series A Warrants [Member] Series A warrants. Vesting Vesting [Axis] Vesting Vesting [Domain] First anniversary Share-based Compensation Award, Tranche One [Member] Monthly vesting over following 3 years Share-based Compensation Award, Tranche Two [Member] First anniversary Share-based Compensation Award, Tranche Three [Member] Monthly vesting over following year Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Four [Member] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] December 2017 December 2017 [Member] December 2017 [Member] Sale of Stock Sale of Stock [Axis] Sale of Stock Sale of Stock [Domain] Secondary Public Offering Secondary Public Offering [Member] Secondary public offering. ESPP Employee Stock [Member] Common stock warrants Award Type Award Type [Axis] Equity Award Equity Award [Domain] Options to purchase common stock Employee Stock Option [Member] Plan Name Plan Name [Axis] Plan Name Plan Name [Domain] 2013 Plan Two Thousand Thirteen Plan [Member] 2013 plan. Shares offered for public offering (in shares) Stock Issued During Period, Shares, New Issues Shares offering price per share (in dollars per share) Sale of Stock, Price Per Share Gross proceeds from secondary public offering Proceeds From Issuance Of Secondary Public Offering Gross Proceeds from issuance of secondary public offering gross. Common stock shares issued (in shares) Shares reserved for issuance under the ESPP (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Offering period Offering Period Offering period. Purchase period Purchase Period Purchase period. Purchase of common stock under ESPP (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Shares Purchased for Award Shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Award vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Stock-based compensation expenses Allocated Share-based Compensation Expense Total stock-based compensation expense capitalized as part of cost of inventory Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Statement of Financial Position [Abstract] Common stock, par value (in usd per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Cash equivalents Cash Equivalents [Member] Commercial paper Commercial Paper [Member] U.S. Government-sponsored enterprise US Government Agencies Debt Securities [Member] U.S. Treasury securities US Treasury Securities [Member] Corporate debt securities Corporate Debt Securities [Member] Measurement Frequency Measurement Frequency [Axis] Fair Value, Measurement Frequency Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Level 2 [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Domain] (Level 1) Fair Value, Inputs, Level 1 [Member] (Level 2) Fair Value, Inputs, Level 2 [Member] (Level 3) Fair Value, Inputs, Level 3 [Member] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Total assets Assets, Fair Value Disclosure Total liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization expense Depreciation, Depletion and Amortization Interest expense related to amortization of debt discount and debt issuance costs Amortization of Debt Issuance Costs and Discounts Provision for allowance for doubtful accounts Provision for Doubtful Accounts Provision for inventories reserve Inventory Write-down Change in fair value of common stock warrants Fair Value Adjustment of Warrants Amortization of premium (discount) on short-term investments Investment Income, Net, Amortization of Discount and Premium Stock-based compensation expense Share-based Compensation Loss on extinguishment of debt Gain (Loss) on Extinguishment of Debt Other Other Operating Activities, Cash Flow Statement Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable, net Increase (Decrease) in Accounts Receivable Inventories, net Increase (Decrease) in Inventories Prepaid and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other long-term assets Increase (Decrease) in Other Noncurrent Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued expenses Increase (Decrease) in Accrued Liabilities Employee-related liabilities Increase (Decrease) in Employee Related Liabilities Deferred revenue Increase (Decrease) in Contract with Customer, Liability Other current liabilities Increase (Decrease) in Other Current Liabilities Deferred rent Increase Decrease In Deferred Rent Increase decrease in deferred rent. Other long-term liabilities Increase (Decrease) in Other Noncurrent Liabilities Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of short-term investments Payments to Acquire Short-term Investments Proceeds from maturities of short-term investments Proceeds from Sale, Maturity and Collection of Short-term Investments Proceeds from sales of short-term investments Proceeds from Sale of Short-term Investments Purchases of property and equipment Payments to Acquire 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 [Abstract] Principal payments on notes payable Repayments of Notes Payable Proceeds from public offering, net of offering costs Proceeds From Public Offering Net Of Offering Costs Cash proceeds received by the Company, net of offering costs, for the initial or subsequent offering of common stock to the public. Proceeds from exercise of common stock warrants Proceeds from Warrant Exercises Proceeds from issuance of common stock under Company stock plans Proceeds from Issuance of Common Stock Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of foreign exchange rate changes on cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Net increase in cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Cash and cash equivalents at end of period Supplemental disclosures of cash flow information Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Supplemental schedule of non-cash investing and financing activities Noncash Investing and Financing Items [Abstract] Right-of-use assets obtained in exchange for operating lease obligations Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Property and equipment included in accounts payable Capital Expenditures Incurred but Not yet Paid Balance at beginning of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Increase in fair value included in change in fair value of common stock warrants Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease) Decrease in fair value from warrants exercised during the period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Balance at end of period Accounting Policies [Abstract] 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 Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities excluded from computation of earnings per share, amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Employee Stock Option [Member] Stock Options Weighted average grant date fair value (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Summary of significant accounting policies. Adjustments for New Accounting Pronouncements Adjustments for New Accounting Pronouncements [Axis] Type of Adoption Type of Adoption [Domain] ASU 2014-09: Revenue from Contracts with Customers [Member] Accounting Standards Update 2014-09 [Member] Complementary products Complementary Products [Member] Complementary products. Tandem Pump Tandem Pump [Member] Tandem pump. Slim cartridges and infusion sets Slim Cartridges And Infusion Sets [Member] Slim cartridges and infusion sets. SEC Schedule, 12-09, Valuation Allowances and Reserves Type SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Warranty reserves SEC Schedule, 12-09, Reserve, Warranty [Member] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Summary of significant accounting policies. Number of operating segments Number of Operating Segments Net reduction to accumulated deficit New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets Revenue performance obligations satisfied over period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Deferred revenue Contract with Customer, Liability, Current Offered period for sales return Offered Period For Sales Return Prior To Expiration Offered period for sales return prior to expiration. Allowance for product returns Allowance For Sales Returns Allowance for sales returns. Warranty period offered Products Warranty Period Products warranty period. Warranty reserve Standard and Extended Product Warranty Accrual Increase in loss used for dilutive calculation Dilutive Securities, Effect on Basic Earnings Per Share Increase in denominator shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Schedule of Future Minimum Payments Under Non-cancellable Operating Leases Lessee, Operating Lease, Liability, Maturity [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Cost of sales Cost of Sales [Member] Selling, general & administrative Selling, General and Administrative Expenses [Member] Research and development Research and Development Expense [Member] Compensation cost Term Loan Agreement Debt Disclosure [Text Block] Inventory Disclosure [Abstract] Raw materials Inventory, Raw Materials, Gross Work-in-process Inventory, Work in Process, Gross Finished goods Inventory, Finished Goods, Gross Total Inventory, Net Summary of Inventories Schedule of Inventory, Current [Table Text Block] Inventories Inventory Disclosure [Text Block] Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Measurement Input Type Measurement Input Type [Axis] Measurement Input Type Measurement Input Type [Domain] Risk-free interest rate Measurement Input, Risk Free Interest Rate [Member] Expected dividend yield Measurement Input, Expected Dividend Rate [Member] Expected volatility Measurement Input, Price Volatility [Member] Expected Term Measurement Input, Expected Term [Member] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Assumptions used to estimate fair value of common stock warrants Warrants and Rights Outstanding, Measurement Input Expected term (in years) Warrants and Rights Outstanding, Term Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Transfer between level 1 and level 2 assets Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Public offering period Public Offering Period Public offering period. Warrants initial value Fair Value Of Warrant Liability Fair value of warrant liability. Warrants expired Class of Warrant or Right, Expired Class of Warrant or Right, Expired Cover page. Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Segment Reporting Segment Reporting, Policy [Policy Text Block] Accounts Receivable Receivables, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Warranty Reserve Standard Product Warranty, Policy [Policy Text Block] Stock-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Net Loss Per Share Earnings Per Share, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward] Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward] Beginning balance Provision for warranties issued during the period Standard and Extended Product Warranty Accrual, Increase for Warranties Issued Settlements made during the period Standard and Extended Product Warranty Accrual, Decrease for Payments Increases in warranty estimates Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties Ending balance Current portion Product Warranty Accrual, Current Non-current portion Product Warranty Accrual, Noncurrent Total Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Assumptions Used to Estimate Fair Values of Common Stock Warrants Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Summary of Changes in Fair Value of Total Level 3 Financial Assets Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Equity [Abstract] Schedule of Shares of Common Stock Reserved for Future Issuance Schedule Of Common Stock Reserved For Future Issuance Table [Text Block] Schedule of common stock reserved for future issuance. Schedule of Assumptions Used in Black-Scholes Option-Pricing Model Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary for Allocation of Stock-Based Compensation Expense Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Leases Lessee, Operating Leases [Text Block] Finite-Lived Intangible Assets by Major Class Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name Finite-Lived Intangible Assets, Major Class Name [Domain] Patents Patents [Member] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Short-term Investments Accounts receivable, net Accounts Receivable, Net, Current Inventories, net Prepaid and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property and equipment, net Property, Plant and Equipment, Net Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Patents, net Finite-Lived Intangible Assets, Net Other long-term 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 expenses Accrued Liabilities, Current Employee-related liabilities Employee-related Liabilities, Current Deferred revenue Deferred revenue Deferred Revenue, Current Common stock warrants Common Stock Warrants Common stock warrants. Operating lease liabilities Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current Deferred rent - long-term Deferred Rent Credit, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 9) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $0.001 par value; 200,000 shares authorized, 59,029 and 57,554 shares issued and outstanding at September 30, 2019 (unaudited) and December 31, 2018, respectively. Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders’ equity Total liabilities and stockholders’ equity Liabilities and Equity Summary of Estimated Fair Value of Short-Term Investments Cash, Cash Equivalents and Investments [Table Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Income Statement [Abstract] Sales Revenue from Contract with Customer, Excluding Assessed Tax Cost of sales Cost of Goods and Services Sold Gross profit Gross Profit Operating expenses: Operating Expenses [Abstract] Selling, general and administrative Selling, General and Administrative Expense Research and development Research and Development Expense Total operating expenses Operating Expenses Operating loss Operating Income (Loss) Other income (expense), net: Other Nonoperating Income (Expense) [Abstract] Interest and other income Interest and Other Income Interest and other expense Interest Expense, Other Loss on extinguishment of debt Change in fair value of stock warrants Total other income (expense), net Other Nonoperating Income (Expense) Loss before income taxes Income (Loss) Attributable to Parent, before Tax Income tax expense Income Tax Expense (Benefit) Net loss Other comprehensive loss: Other Comprehensive Income (Loss), Net of Tax [Abstract] Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net loss per share, basic (in dollars per share) Earnings Per Share, Basic Net loss per share, diluted (in dollars per share) Earnings Per Share, Diluted Weighted average shares used to compute basic net loss per share (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average shares used to compute diluted net loss per share (in shares) Weighted Average Number of Shares Outstanding, Diluted Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Maximum Maximum [Member] Cash equivalents maturity term Cash Equivalents Maturity Term Cash equivalents maturity term. Cash Cash Equivalents And Short Term Investments [Table] Cash Cash Equivalents And Short Term Investments [Table] Cash cash equivalents and short term investments. Investment Type Investment Type [Axis] Investments Investments [Domain] U.S. Government-sponsored enterprise US Government-sponsored Enterprises Debt Securities [Member] Cash Cash Equivalents And Short Term Investments [Line Items] Cash Cash Equivalents And Short Term Investments [Line Items] Cash cash equivalents and short term investments. Available-for-sale securities, Maturity (in years) Short Term Investments Maturity Short term investments maturity. Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Gross Unrealized Gain Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Loss Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Estimated Fair Value Debt Securities, Available-for-sale Short-term investments, Amortized Cost Short Term Investments Amortized Cost Short term investments amortized cost. Short-term investments, Unrealized Gain Short Term Investments Accumulated Gross Unrealized Gain Before Tax Short term investments accumulated gross unrealized gain before tax. Short-term investments, Unrealized Loss Short Term Investments Accumulated Gross Unrealized Loss Before Tax Short term investments accumulated gross unrealized loss before tax. Short-term investments, Estimated Fair Value Debt Securities, Available-for-sale, Current Summary of Reconciliation of Change in Product Warranty Liabilities Schedule of Product Warranty Liability [Table Text Block] Schedule of Anti-Dilutive Securities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Lease Arrangements [Axis] Lease Arrangements [Axis] Lease Arrangements [Axis] Lease Arrangements [Domain] Lease Arrangements [Domain] [Domain] for Lease Arrangements [Axis] Vista Sorrento Original Lease Vista Sorrento Lease [Member] Vista Sorrento Lease [Member] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Domain] Difference Between Leases Guidance in Effect Before and After Topic 842 Difference Between Leases Guidance In Effect Before And After Topic842 [Member] Difference between leases guidance in effect before and after Topic 842. Balance Sheet Location Balance Sheet Location [Axis] Balance Sheet Location Balance Sheet Location [Domain] Other Current Liabilities Other Current Liabilities [Member] Geographical Geographical [Axis] Geographical Geographical [Domain] 10935 Vista Sorrento Parkway, San Diego, California Vista Sorrento Parkway [Member] Vista Sorrento Parkway. 6495 Marindustry Place, San Diego, California Marindustry Place [Member] Marindustry Place. Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Operating Lease, Liability Deferred rent, current Deferred Rent Credit, Current Deferred rent—long-term Maximum lease period to not recognize right of use assets or lease liabilities Lessee, Operating Lease, Term of Contract Area of office space leased Area of Real Estate Property Operating lease extension period Lessee, Operating Lease, Renewal Term