Entity Central Index Key Document And Entity Information [Abstract] 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 Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Current Reporting Status Entity Current Reporting Status Entity Shell Company Entity Shell Company Entity File Number Entity File Number Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Fair value of outstanding redeemable nonconvertible preferred stock. 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 marketable securities Available For Sale Securities Debt Securities Current Accounts receivable Accounts Receivable Net Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Long-term marketable securities Available For Sale Securities Debt Securities Noncurrent Property and equipment, net Property Plant And Equipment Net Deferred tax assets Deferred Tax Assets Liabilities Net Noncurrent Restricted cash Restricted Cash And Cash Equivalents Noncurrent Other long-term assets Other Assets Noncurrent Total assets Assets Liabilities and Stockholders' Equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued expenses and other current liabilities Accrued Liabilities Current Income taxes payable Accrued Income Taxes Current Total current liabilities Liabilities Current Series 1 nonconvertible preferred stock Non Convertible Preferred Stock Liabilities Other long-term liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 11) Commitments And Contingencies Stockholders' equity: Stockholders Equity [Abstract] Common stock; $0.01 par value per share, 100,000 shares authorized; 19,682 and 19,395 shares issued and outstanding at June 30, 2019 and September 30, 2018, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income Loss Net Of Tax Retained earnings Retained Earnings Accumulated Deficit Total stockholders' equity Stockholders Equity Total liabilities and stockholders' equity Liabilities And Stockholders Equity Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, shares authorized Common Stock Shares Authorized Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service Product Or Service [Axis] Product and Service Products And Services [Domain] Royalties [Member] Royalty [Member] Milestone. Milestone [Member] Milestone [Member] Statement [Line Items] Statement [Line Items] Revenue Revenues [Abstract] Total revenue Revenue From Contract With Customer Excluding Assessed Tax Operating expenses: Operating Costs And Expenses [Abstract] Research and development Research And Development Expense General and administrative General And Administrative Expense Total operating expenses Costs And Expenses Income from operations Operating Income Loss Other income, net Nonoperating Income Expense Income before income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Income tax (expense) benefit Income Tax Expense Benefit Net income Net Income Loss Net income per share: Earnings Per Share [Abstract] Basic Earnings Per Share Basic Diluted Earnings Per Share Diluted Weighted average shares outstanding: Weighted Average Number Of Shares Outstanding Diluted Disclosure Items [Abstract] Basic Weighted Average Number Of Shares Outstanding Basic Diluted Weighted Average Number Of Diluted Shares Outstanding Statement Of Income And Comprehensive Income [Abstract] Net income Other comprehensive income (loss): Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Net unrealized gains (losses) on marketable securities, net of tax of $56, $76, $179 and ($159) Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax Total other comprehensive income (loss), net of tax Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Comprehensive income, net of tax Comprehensive Income Net Of Tax Net unrealized gains (losses) on marketable securities, tax Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax Stock issued during period shares stock options and warrants exercised. Stock issued during period value stock options and warrants exercised. Statement Of Stockholders Equity [Abstract] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid In Capital [Member] Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive Income [Member] Retained Earnings [Member] Retained Earnings [Member] Beginning Balance Beginning Balance, Shares Shares Issued Exercise of stock options and warrants Stock Issued During Period Value Stock Options And Warrants Exercised Exercise of stock options and warrants, Shares Stock Issued During Period Shares Stock Options And Warrants Exercised Exercise of stock options Stock Issued During Period Value Stock Options Exercised Exercise of stock options, Shares Stock Issued During Period Shares Stock Options Exercised Vesting of restricted stock units, net of withholding Restricted Stock Value Shares Issued Net Of Tax Withholdings Vesting of restricted stock units, net of withholding, Shares Restricted Stock Shares Issued Net Of Shares For Tax Withholdings Stock-based compensation expense Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Cumulative effect adjustment for adoption of new accounting guidance Cumulative Effect Of New Accounting Principle In Period Of Adoption Other comprehensive income (loss), net of tax Ending Balance Ending Balance, Shares The cash outflow associated with the premium paid on marketable securities. Statement Of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided By Used In Operating Activities [Abstract] Net income Profit Loss Adjustments to reconcile net income to net cash provided by operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Stock-based compensation expense Share Based Compensation Depreciation and amortization expense Depreciation And Amortization Deferred income taxes Deferred Income Taxes And Tax Credits Premium paid on marketable securities Premium On Marketable Securities Accretion of discount on marketable securities Accretion Amortization Of Discounts And Premiums Investments Change in fair value of warrant liability and Series 1 nonconvertible preferred stock Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net Other non-cash items Other Noncash Income Expense Change in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Accounts payable Increase Decrease In Accounts Payable Accrued expenses Increase Decrease In Accrued Liabilities Income taxes payable Increase Decrease In Accrued Income Taxes Payable Other long-term liabilities Increase Decrease In Other Noncurrent Liabilities Net cash provided by operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities Net Cash Provided By Used In Investing Activities [Abstract] Purchase of marketable securities Payments To Acquire Marketable Securities Proceeds from maturities and sale of marketable securities Proceeds From Sale And Maturity Of Available For Sale Securities Purchase 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 Cash flows from financing activities Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from exercise of stock options and warrants Proceeds From Issuance Or Sale Of Equity Payments for settlement of share-based awards Payments Related To Tax Withholding For Share Based Compensation Payments of capital lease obligations Repayments Of Long Term Capital Lease Obligations Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Net increase (decrease) in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash, cash equivalents and restricted cash at end of period Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for income taxes Income Taxes Paid Supplemental disclosure of non-cash investing information: Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Purchases of fixed assets included in accounts payable and accrued expenses Capital Expenditures Incurred But Not Yet Paid Organization Consolidation And Presentation Of Financial Statements [Abstract] Nature of the Business and Basis of Presentation Business Description And Basis Of Presentation [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Assets and Liabilities Fair Value Disclosures [Text Block] Investments Debt And Equity Securities [Abstract] Marketable Securities Investments In Debt And Marketable Equity Securities And Certain Trading Assets Disclosure [Text Block] Payables And Accruals [Abstract] Accrued Expenses and Other Long-Term Liabilities Accounts Payable And Accrued Liabilities Disclosure [Text Block] Ongoing Collaboration Agreements Collaborative Arrangement Disclosure [Text Block] Nonconvertible preferred stock. Debt Disclosure [Abstract] Series 1 Nonconvertible Preferred Stock Nonconvertible Preferred Stock [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Awards Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Net Income Per Share Earnings Per Share [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Use of Estimates Use Of Estimates Revenue Recognition Revenue Recognition Policy [Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis Table [Text Block] Fair Value Measurements of the Company's Outstanding Series 1 Nonconvertible Preferred Stock Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques Table [Text Block] Roll-forward of Aggregate Fair Value of Outstanding Series 1 Nonconvertible Preferred Stock Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Text Block] Fair Value of Available-for-Sale Marketable Securities Schedule Of Available For Sale Securities Reconciliation Table [Text Block] Accrued Expenses and Other Current Liabilities as well as Other Long-Term Liabilities Schedule Of Accrued Liabilities Table [Text Block] Award Type Award Type [Axis] Equity Award Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Performance share units and relative stockholder return units. Performance Share Units and Relative Total Stockholder Return Units [Member] Performance Share Units And Relative Stockholder Return Units [Member] Summary of Stock Option Activity Including Performance Based Options Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Summary of PSUs and rTSRUs Activity Based on Targeted Number of Shares Schedule Of Nonvested Performance Based Units Activity Table [Text Block] Summary of Restricted Stock Unit Activity Schedule Of Nonvested Restricted Stock Units Activity Table [Text Block] Stock-Based Compensation Expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Basic and Diluted Net Income Per Share Attributable to Common Stockholders Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Entity incorporated, in year Year Founded Entity incorporation, state country name Entity Incorporation State Country Name Summary of Accounting and Financial Policies [Line Items] Summary of Accounting and Financial Policies [Table] Summary Of Accounting And Financial Policies [Table] Summary Of Accounting And Financial Policies [Table] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] ASU 2016-18 [Member] Accounting Standards Update201618 [Member] Summary Of Accounting And Financial Policies [Line Items] Summary Of Accounting And Financial Policies [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Investment Type Investment Type [Axis] Investments Investment Type Categorization [Member] Money Market Funds [Member] Money Market Funds [Member] Corporate Bonds [Member] Corporate Debt Securities [Member] Commercial Paper [Member] Commercial Paper [Member] U.S. Treasury Notes [Member] U S Treasury Securities [Member] Level 2 [Member] Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value Inputs Level1 [Member] Level 2 [Member] Fair Value Inputs Level2 [Member] Level 3 [Member] Fair Value Inputs Level3 [Member] Class of Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Preferred stock that may not be exchanged into common shares or other types of securities at the owner's option. Series 1 Nonconvertible Preferred Stock [Member] Series One Non Convertible Preferred Stock [Member] 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] Assets: Assets Fair Value Disclosure [Abstract] Cash equivalents Cash And Cash Equivalents Fair Value Disclosure Marketable securities Available For Sale Securities Debt Securities Assets, Fair Value Disclosure, Total Assets Fair Value Disclosure Liabilities: Liabilities Fair Value Disclosure [Abstract] Liabilities Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value Liabilities, Fair Value Disclosure, Total Liabilities Fair Value Disclosure Amount of transfers of financial instruments classified as an asset or liability between level 1, level 2, and level 3 of the fair value hierarchy. Transfers between Level 1, Level 2 and Level 3 Fair Value Measurements Inter Transfers Between Levels Nonconvertible preferred stock measurement input. Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Table] Range Range [Axis] Range Range [Member] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Measurement Input Type Measurement Input Type [Axis] Measurement Input Type Measurement Input Type [Domain] Measurement input probabilities of payout. Probabilities of Payout [Member] Measurement Input Probabilities Of Payout [Member] Discount Rate [Member] Measurement Input Discount Rate [Member] Fair Value Inputs, Liabilities, Quantitative Information [Line Items] Range (Weighted Average) Nonconvertible Preferred Stock Measurement Input Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table] Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] Beginning Balance Change in fair value of nonconvertible preferred stock Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Period Increase Decrease Ending Balance Schedule Of Available For Sale Securities [Table] Schedule Of Available For Sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Schedule Of Available For Sale Securities [Line Items] Amortized Cost Available For Sale Debt Securities Amortized Cost Basis Gross Unrealized Gains Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Gross Unrealized Losses Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Fair Value Description of period of maturity for investments classified as marketable securities. Short term marketable securities. Short Term Marketable Securities [Member] Short Term Marketable Securities [Member] Corporate Bonds and U.S. Treasury Notes [Member] Corporate Bonds and U.S. Treasury Notes [Member] Corporate Bonds And U S Treasury Notes [Member] Investment Securities Class Investment Securities Class [Axis] Investment Securities Class Investment Securities Class [Domain] Long term marketable securities. Long Term Marketable Securities [Member] Long Term Marketable Securities [Member] Maturity period of the marketable securities Marketable Securities Maturity Period Carrying value as of the balance sheet date of obligations incurred and payable for preclinical and clinical expenses (due within one year or within the normal operating cycle if longer). Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs for manufacturing of materials. Accrued expenses: Accrued Liabilities Current [Abstract] Accrued preclinical and clinical expenses Accrued Preclinical And Clinical Expenses Current Accrued payroll and related expenses Employee Related Liabilities Current Accrued vendor manufacturing Accrued Liabilities Manufacturing Accrued professional fees Accrued Professional Fees Current Accrued other Other Accrued Liabilities Current Accrued expenses Other long-term liabilities: Other Liabilities Noncurrent [Abstract] Uncertain tax positions Liability For Uncertain Tax Positions Noncurrent Accrued rent expense Accrued Rent Noncurrent Capital lease obligation Capital Lease Obligations Noncurrent Asset retirement obligation Asset Retirement Obligations Noncurrent Other long-term liabilities Cash consideration received under collaboration from sale of preferred stock, research funding payments, milestone payments and royalties. Collaboration agreements remaining milestone payments to be earned. Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Type of Arrangement and Non-arrangement Transactions Type Of Arrangement [Axis] Arrangements and Non-arrangement Transactions Arrangements And Nonarrangement Transactions [Member] AbbVie. AbbVie [Member] Abb Vie [Member] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] JAPAN [Member] JAPAN Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Cash consideration received under collaboration from sale of preferred stock, research funding payments, milestone payments and royalties Cash Consideration Received Under Collaboration From Sale Of Preferred Stock Research Funding Payments Milestone Payments And Royalties Revenue recognized Type of cost, good or service [Extensible List] Type Of Revenue Extensible List Remaining milestone payments to be earned Collaboration Agreements Remaining Milestone Payments To Be Earned Collaboration agreement tiered royalty description Collaborative Arrangement Rights And Obligations Equity [Abstract] Schedule Of Stock By Class [Table] Schedule Of Stock By Class [Table] Class Of Stock [Line Items] Class Of Stock [Line Items] Preferred stock, shares issued Preferred Stock Shares Issued Preferred stock, shares outstanding Preferred Stock Shares Outstanding Options Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward Outstanding as of beginning of period Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Exercised Forfeited Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Outstanding as of end of period Options vested and expected to vest as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number Options exercisable as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Weighted Average Exercise Price Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Rollforward Outstanding Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Granted Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Exercised Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Forfeited Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price Outstanding Options vested and expected to vest as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price Options exercisable as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Weighted Average Remaining Contractual Term Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract] Outstanding as of end of period Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 Options vested and expected to vest as of end period Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1 Options exercisable as of end of period Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 Share based compensation arrangement by share based payment award options aggregate intrinsic value. Aggregate Intrinsic Value Share Based Compensation Arrangement By Share Based Payment Award Options Aggregate Intrinsic Value [Abstract] Outstanding as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Options vested and expected to vest as of end of period Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value Options exercisable as of end of period Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 The percentage of target performance shares that are eligible to be earned based on achievement of a total shareholder return target. Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Title of Individual Title Of Individual [Axis] Relationship to Entity Title Of Individual With Relationship To Entity [Domain] Executive Officers [Member] Executive Officer [Member] Relative stockholder return units rTSRUs. Relative Total Stockholder Return Units [Member] Relative Stockholder Return Units R T S R Us [Member] PSUs [Member] Performance Shares [Member] Restricted Stock Units [Member] Restricted Stock Units R S U [Member] Vesting Vesting [Axis] Vesting Vesting [Domain] Tranche One [Member] Share Based Compensation Award Tranche One [Member] Tranche Two [Member] Share Based Compensation Award Tranche Two [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Number of shares range percentage Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Shares Earned Share Based Arrangements To Obtain Goods And Services [Abstract] rTSRUs [Member] Unvested, beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Granted Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Cancelled Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Unvested, ending balance Weighted Average Grant Date Fair Value, Unvested beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Granted Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Cancelled Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Unvested ending balance Vesting percentage Sharebased Compensation Arrangement By Sharebased Payment Award Award Vesting Rights Percentage Aggregate target share issued on vesting, net of share withholding Vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and Development [Member] Research And Development Expense [Member] General and Administrative [Member] General And Administrative Expense [Member] Stock Options [Member] Employee Stock Option [Member] Performance Stock Units [Member] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Stock-based compensation expense Allocated Share Based Compensation Expense Aggregate of unrecognized stock-based compensation cost Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Weighted average recognition period Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Basic net income per share: Earnings Per Share Basic [Abstract] Weighted average common shares outstanding—basic Net income per share common share—basic Diluted net income per share: Earnings Per Share Diluted [Abstract] Dilutive effect of common stock equivalents Weighted Average Number Diluted Shares Outstanding Adjustment Weighted average common shares outstanding—diluted Net income per share common share—diluted Anti-dilutive common stock equivalents excluded from above Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Amount of income tax expense (benefit) for remeasurement of deferred tax from change in tax rate pursuant to Tax Cuts and Jobs Act. Effective tax rates Effective Income Tax Rate Continuing Operations Federal statutory rate Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate Income tax expense as a result of U.S. Tax Cuts and Jobs Act Tax Cuts And Jobs Act Of2017 Change In Tax Rate Income Tax Expense Benefit Unrecognized tax benefits Unrecognized Tax Benefits Number of leases. Commitments And Contingencies [Line Items] Commitments And Contingencies [Table] Commitments And Contingencies [Table] Commitments And Contingencies [Table] Lease Arrangement, Type Lease Arrangement Type [Axis] Lease Arrangement, Type Lease Arrangement Type [Domain] First lease. First Lease [Member] First Lease [Member] Second lease. Second Lease [Member] Second Lease [Member] Watertown, Massachusetts [Member] MASSACHUSETTS Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Number of leases Number Of Leases Office lease expiration period Lease Expiration Date1 Rent expense Lease And Rental Expense Outstanding letter of credit Letters Of Credit Outstanding Amount Long term restricted cash