Number of customers accounted for more than ten percent of accounts receivable.

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- Definition

Number of customers accounted for more than ten percent of product revenue.

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No definition available.

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- Definition

Number of major customers.

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No definition available.

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- Definition

Summary of significant accounting policies.

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No definition available.

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- Definition

Trade payment term.

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No definition available.

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- Definition

Amount of direct write-downs of accounts receivable charged against the allowance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
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- Definition

Amount of amortization expense attributable to debt issuance costs.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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No definition available.

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Face (par) amount of debt instrument at time of issuance.

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Amount, after accumulated amortization, of debt issuance costs classified as current. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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-Name Accounting Standards Codification
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-SubTopic 20
-Section 45
-Paragraph 1
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- Definition

Amount of lessee's right to use underlying asset under operating lease.

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Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) Customer	Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)	May 02, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accounts written off	$ 0	$ 0
Carrying value of debt issuance costs reported in prepaid expenses and other current assets	2,900,000	3,500,000
Amortization of debt issuance costs recognized as other expense	$ 600,000	$ 600,000	$ 400,000
Concentration risk, percentage	10.00%	10.00%
Number of customers accounted for more than 10% of accounts receivable \| Customer	0	0
Number of customers accounted for more than 10% of net product revenue \| Customer	0	0
Operating lease liabilities				$ 7,000,000.0
Right-of-use assets	$ 8,223,000	$ 0		$ 6,600,000
2024 Convertible Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Convertible Notes, face value	201,300,000				$ 201,300,000
Estimated fair value of Convertible Notes	$ 215,700,000
Customer Concentration Risk [Member] \| Total Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of major customers \| Customer	3	2
Concentration risk, percentage	84.00%	81.00%
Customer Concentration Risk [Member] \| Total Revenue [Member] \| Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	44.00%	49.00%
Customer Concentration Risk [Member] \| Total Revenue [Member] \| Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	25.00%	32.00%
Customer Concentration Risk [Member] \| Total Revenue [Member] \| Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	15.00%
Customer Concentration Risk [Member] \| Total Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of major customers \| Customer	4	2
Concentration risk, percentage	93.00%	82.00%
Customer Concentration Risk [Member] \| Total Accounts Receivable [Member] \| Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	42.00%	52.00%
Customer Concentration Risk [Member] \| Total Accounts Receivable [Member] \| Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	11.00%	30.00%
Customer Concentration Risk [Member] \| Total Accounts Receivable [Member] \| Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	20.00%
Customer Concentration Risk [Member] \| Total Accounts Receivable [Member] \| Customer Four [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	20.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Trade payment term	1 year