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Significant Accounting Policies - Additional Information (Detail) | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2020 USD ($) Segment Customer | Sep. 30, 2019 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2012 USD ($)
Significant Accounting Policies [Line Items] |  |  |  |
Trade receivables, credit period | 30 days |  |  |
Maturities period | 24 months |  |  |
Unrealized gain on held-to-maturity securities | $ 900,000 |  |  |
Number of operating segments | Segment | 1 |  |  |
ASU No. 2018-18 |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect [true false] | true |  |  |
ASU No. 2018-13 |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect [true false] | true |  |  |
ASU No. 2016-13 |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect [true false] | true |  |  |
Minimum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Trade receivables, credit period | 30 days |  |  |
Maximum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Trade receivables, credit period | 60 days |  |  |
Embedded Derivative Financial Instruments | BioPharma Debt |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Maximum repayment of future revenue and receivables |  |  |  | $ 150,000,000.0
Fair value of embedded derivative liability | $ 0 |  | $ 0 |
Gain (loss) on change in fair value of derivative liabilities | $ 0 | $ 0 |  |
Embedded Derivative Financial Instruments | BioPharma Debt | Minimum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Derivative liability fair value assumption, coupon rate | 6.00% |  | 6.00% |
Derivative liability fair value assumptions, market yields | 5.40% |  | 5.20% |
Embedded Derivative Financial Instruments | BioPharma Debt | Maximum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Derivative liability fair value assumption, coupon rate | 11.50% |  | 11.50% |
Derivative liability fair value assumptions, market yields | 16.40% |  | 16.80% |
Embedded Derivative Financial Instruments | BioPharma Debt | Measurement Input, Expected Term | Minimum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Derivative liability fair value assumptions, term | 1 year 2 months 12 days |  | 1 year 10 months 24 days |
Embedded Derivative Financial Instruments | BioPharma Debt | Measurement Input, Expected Term | Maximum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Derivative liability fair value assumptions, term | 6 years 6 months |  | 7 years 3 months 18 days |
Short Term Investments |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Maturities period | 12 months |  |  |
Long Term Investments |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Maturities period | 12 months |  |  |
Money Market Instruments |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Maturities period | 90 days |  |  |
Gross Product Sales | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Number of customers | Customer | 3 |  |  |
Customer A | Gross Product Sales | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 25.00% | 25.00% |  |
Customer A | Accounts Receivable | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 37.00% | 42.00% |  |
Customer B | Gross Product Sales | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 37.00% | 36.00% |  |
Customer B | Accounts Receivable | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 32.00% | 23.00% |  |
Customer C | Gross Product Sales | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 30.00% | 29.00% |  |
Customer C | Accounts Receivable | Customer Concentration Risk |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Concentration risk percentage | 25.00% | 28.00% |  |

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