v3.19.3.a.u2

Summary of Significant Accounting Policies - Accounting Policies Narrative (Details) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 USD ($) segment shares | Dec. 31, 2018 USD ($) shares | Dec. 31, 2017 USD ($) shares | Jan. 01, 2019 USD ($) | Dec. 11, 2018 shares
Accounting Policies [Abstract] |  |  |  |  |
Number of operating segments | segment | 1 |  |  |  |
Impairment charges related to marketable securities | $ 0 | $ 0 | $ 0 |  |
Allowance for doubtful accounts | 0 | 0 |  |  |
Bad debt expense | 0 | 0 | 0 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Impairment of long-lived assets | 0 | 0 | $ 0 |  |
Decrease in deferred tax asset | (507,268,000) | (323,501,000) |  |  |
Valuation allowance | 470,753,000 | 308,273,000 |  |  |
Remaining deferred revenues | 199,528,000 | $ 240,924,000 |  |  |
Right-of-use assets, operating leases | 86,414,000 |  |  | $ 63,334,000 |
Operating lease, liability | $ 97,259,000 |  |  |  |
Redeemable convertible preferred stock, shares issued | shares | 0 | 0 | 448,686,791 |  | 508,539,515
Redeemable convertible preferred stock, shares outstanding | shares | 0 | 0 | 448,686,791 |  | 508,539,515
Minimum |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Debt instrument term | 12 months |  |  |  |
Marketable securities maturity term | 12 months |  |  |  |
Maximum |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Marketable securities maturity term | 12 months |  |  |  |
Accounting Standards Update 2014-09 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in cumulative effect of applying new standard |  |  |  | 27,984,000 |
Decrease in deferred tax asset |  |  |  | 8,400,000 |
Valuation allowance |  |  |  | (8,400,000) |
Increase (decrease) in deferred revenue |  |  |  | (30,700,000) |
Accounting Standards Update 2016-02 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in cumulative effect of applying new standard |  |  |  | (3,790,000) |
Right-of-use assets, operating leases |  |  |  | 63,300,000 |
Operating lease, liability |  |  |  | 70,700,000 |
Accumulated Deficit | Accounting Standards Update 2014-09 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in cumulative effect of applying new standard |  |  |  | 27,984,000 |
Accumulated Deficit | Accounting Standards Update 2016-02 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in cumulative effect of applying new standard |  |  |  | (3,790,000) |
Combined 2018 AZ Agreements |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Remaining deferred revenues | $ 73,700,000 | $ 115,600,000 |  | 75,700,000 |
Combined 2018 AZ Agreements | Accounting Standards Update 2014-09 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in deferred revenue |  |  |  | 39,900,000 |
PCVSAV Agreement |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Remaining deferred revenues | 83,800,000 | 111,300,000 |  | 125,200,000 |
PCVSAV Agreement | Accounting Standards Update 2014-09 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in deferred revenue |  |  |  | 13,900,000 |
VEGF Exercise 2016 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Remaining deferred revenues | 41,200,000 | 41,200,000 |  | 37,100,000 |
VEGF Exercise 2016 | Accounting Standards Update 2014-09 |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Increase (decrease) in deferred revenue |  |  |  | $ 4,300,000 |
IPO | Common Stock |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Preferred stock converted into common stock (in shares) | shares |  |  |  |  | 236,012,913
Fair Value, Inputs, Level 1 | Nonrecurring |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Letters of credit | $ 11,800,000 | $ 12,100,000 |  |  |

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