Entity Central Index Key Prepayments for equipment. Amortization of deferred income. Increase decrease in long term deposits. Payments to acquire cost method investment. Proceeds from sale disposal of cost method investment. Document and entity information. Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Emerging Growth Company Entity Emerging Growth Company Entity Ex Transition Period Entity Ex Transition Period Entity Shell Company Entity Shell Company 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 Short Term Investments Accounts receivable Accounts Receivable Net Current Inventories Inventory Net Prepayments and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Investments in equity investees Long Term Investments Prepayments for equipment Prepayments For Equipment Property and equipment, net Property Plant And Equipment Net Intangible assets, net Intangible Assets Net Excluding Goodwill Long term deposits Deposits Assets Noncurrent Value added tax recoverable Value Added Tax Receivable Noncurrent Total assets Assets Liabilities and shareholders' equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Short-term borrowings Short Term Borrowings Accounts payable Accounts Payable Current Other payables Other Liabilities Current Total current liabilities Liabilities Current Deferred income Contract With Customer Liability Total liabilities Liabilities Commitments and contingencies (Note 19) Commitments And Contingencies Shareholders' equity Stockholders Equity [Abstract] Ordinary shares (par value of US$0.00006 per share; 83,333,333 shares authorized, 49,912,570 and 58,006,967 shares issued and outstanding as of December 31,2017 and 2018, respectively) Common Stock Value Subscription receivable Common Stock Share Subscribed But Unissued Subscriptions Receivable Additional paid-in capital Additional Paid In Capital Common Stock Accumulated deficit Retained Earnings Accumulated Deficit Accumulated other comprehensive income Accumulated Other Comprehensive Income Loss Net Of Tax Total shareholders' equity Stockholders Equity Total liabilities and shareholders' equity Liabilities And Stockholders Equity Ordinary shares, par value Common Stock Par Or Stated Value Per Share Ordinary shares, shares authorized Common Stock Shares Authorized Ordinary shares, shares issued Common Stock Shares Issued Ordinary shares, shares outstanding Common Stock Shares Outstanding Income Statement [Abstract] Revenue Revenue From Contract With Customer Excluding Assessed Tax Cost of sales Cost Of Revenue Gross profit Gross Profit Operating expenses: Operating Expenses [Abstract] Research and development Research And Development Expense Selling, general and administrative Selling General And Administrative Expense Loss from operations Operating Income Loss Interest income Investment Income Interest Interest expense Interest Expense Changes in fair value of warrants Fair Value Adjustment Of Warrants Other income Other Nonoperating Income Other expense Other Nonoperating Expense Loss before income tax and share of loss from equity method investment Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments Income tax expense Income Tax Expense Benefit Share of loss from equity method investment Income Loss From Equity Method Investments Net loss Net Income Loss Net loss attributable to ordinary shareholders Net Income Loss Available To Common Stockholders Basic Loss per share - basic and diluted Earnings Per Share Basic And Diluted Weighted-average shares used in calculating net loss per ordinary share - basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Statement Of Income And Comprehensive Income [Abstract] Net loss Other comprehensive (loss) income, net of tax of nil: Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Foreign currency translation adjustments Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Other comprehensive (loss) income, tax Other Comprehensive Income Loss Tax Stock issued during period shares warrants exercised. Stock issued during period value warrants exercised. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Ordinary Shares Common Stock [Member] Additional Paid In Capital Additional Paid In Capital [Member] Subscription Receivable Receivables From Stockholder [Member] Accumulated Deficit Retained Earnings [Member] Accumulated Other Comprehensive Loss (Income) Accumulated Other Comprehensive Income [Member] Statement [Line Items] Statement [Line Items] Balance Balance, Shares Issuance of ordinary shares upon vesting of restricted shares Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures Issuance of ordinary shares upon vesting of restricted shares, Shares Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures Exercise of shares option Stock Issued During Period Value Stock Options Exercised Exercise of shares option, Shares Stock Issued During Period Shares Stock Options Exercised Exercise of warrant Stock Issued During Period Value Warrants Exercised Exercise of warrant, Shares Stock Issued During Period Shares Warrants Exercised Conversion of convertible preferred shares to ordinary shares Stock Issued During Period Value Conversion Of Convertible Securities Conversion of convertible preferred shares to ordinary shares, Shares Stock Issued During Period Shares Conversion Of Convertible Securities Issuance of ordinary shares upon initial public offering/ follow-on public offering, net of issuance cost Stock Issued During Period Value New Issues Issuance of ordinary shares upon initial public offering/ follow-on public offering, net of issuance cost, Shares Stock Issued During Period Shares New Issues Share-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Balance Balance, Shares Share issuance cost. Share issuance cost upon initial/follow-on public offering Share Issuance Cost Non-cash payables for intangible assets. Payables for initial public offering costs. Exercise of warrants. Statement Of Cash Flows [Abstract] Operating activities Net Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net loss to net cash provided by operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Depreciation of property and equipment Depreciation Amortization of intangible assets Amortization Of Intangible Assets Amortization of deferred income Amortization Of Deferred Income Share-based compensation Share Based Compensation Share of loss from equity method investment Loss on disposal of property and equipment Gain Loss On Sale Of Property Plant Equipment Change in fair value of warrants Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Inventories Increase Decrease In Inventories Prepayments and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Long term deposits Increase Decrease In Long Term Deposits Value added tax recoverable Increase Decrease In Income Taxes Receivable Accounts payable Increase Decrease In Accounts Payable Other payables Increase Decrease In Other Accounts Payable Deferred income Increase Decrease In Contract With Customer Liability Net cash used in operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities: Net Cash Provided By Used In Investing Activities [Abstract] Purchases of short-term investments Payments To Acquire Short Term Investments Purchase of cost method investment Payments To Acquire Cost Method Investment Disposal of cost method investment Proceeds From Sale Disposal Of Cost Method Investment Purchase of equity method investment Payments To Acquire Equity Method Investments Purchase of property and equipment Payments To Acquire Property Plant And Equipment Disposal of property and equipment Proceeds From Sale Of Property Plant And Equipment Purchase of intangible assets Payments To Acquire Intangible Assets 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] Proceed from short-term borrowings Proceeds From Short Term Debt Proceed from issuance of convertible preferred shares, net of issuance cost Proceeds From Issuance Of Convertible Preferred Stock Proceeds from exercise of warrants Proceeds From Warrant Exercises Proceeds from exercises of stock options Proceeds From Stock Options Exercised Proceeds from issuance of ordinary shares upon public offerings Proceeds From Issuance Initial Public Offering Payment 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 foreign exchange rate changes on cash and cash equivalents Effect Of Exchange Rate On Cash And Cash Equivalents Continuing Operations Net increase (decrease) in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents - beginning of the year Cash and cash equivalents - end of the year Supplemental disclosure on non-cash investing and financing activities: Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Payables for purchase of property and equipment Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 Payables for intangible assets Non Cash Payables For Intangible Assets Payables for public offering costs Payables For Initial Public Offering Costs Conversion of convertible preferred shares Conversion Of Stock Amount Converted1 Exercise of warrants Exercise Of Warrants Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Interest expense paid Interest Paid Net Organization Consolidation And Presentation Of Financial Statements [Abstract] Organization and Principal Activities Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Accounting Policies [Abstract] Summary of significant accounting policies Significant Accounting Policies [Text Block] Cash And Cash Equivalents [Abstract] Cash and Cash Equivalents Cash And Cash Equivalents Disclosure [Text Block] Short-term investment. Short-term investment. Short Term Investment [Abstract] Short-term investment Short Term Investment [Text Block] Inventory Disclosure [Abstract] Inventories Inventory Disclosure [Text Block] Equity and cost method investment. Equity And Cost Method Investment [Abstract] Investments in equity investees Cost And Equity Method Investments Disclosure [Text Block] Property Plant And Equipment [Abstract] Property and Equipment, net Property Plant And Equipment Disclosure [Text Block] Income Tax Disclosure [Abstract] Income tax Income Tax Disclosure [Text Block] Other Liabilities Current [Abstract] Short-term Borrowings Short Term Debt [Text Block] Other current liabilities disclosure. Other Payables Other Current Liabilities Disclosure [Text Block] Convertible preferred shares and warrants. Temporary Equity Disclosure [Abstract] Convertible preferred shares and warrants Convertible Preferred Shares And Warrants Disclosure [Text Block] Earnings Per Share [Abstract] Loss per share Earnings Per Share [Text Block] Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Share-based compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Equity [Abstract] Accumulated Other Comprehensive Loss Comprehensive Income Note [Text Block] Licenses and collaborative arrangement disclosure. Research And Development [Abstract] Licenses and collaborative arrangement Licenses And Collaborative Arrangement Disclosure [Text Block] Restricted net assets . Restricted Net Assets [Abstract] Restricted net assets Restricted Assets Disclosure [Text Block] Compensation And Retirement Disclosure [Abstract] Employee defined contribution plan Compensation And Employee Benefit Plans Other Than Share Based Compensation [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Subsequent Events [Abstract] Subsequent events Subsequent Events [Text Block] Condensed Financial Information Of Parent Company Only Disclosure [Abstract] Financial Statements Schedule I Condensed Financial Information Of Parent Company Only Disclosure [Text Block] Basis of presentation Basis Of Accounting Policy Policy [Text Block] Principles of consolidation Consolidation Policy [Text Block] Use of estimates Use Of Estimates Foreign currency translation Foreign Currency Transactions And Translations Policy [Text Block] Cash and cash equivalents Cash And Cash Equivalents Policy [Text Block] Short term investments policy. Short-term investments Short Term Investments Policy [Text Block] Accounts receivable Receivables Policy [Text Block] Inventories Inventory Policy [Text Block]