Product Revenue Reserves and Allowances - Additional Information (Detail)	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Entity Wide Revenue Major Customer [Line Items]
Allowance for doubtful accounts	$ 0	$ 0
3PL [Member] \| Product Revenue [Member] \| Total Revenues [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	39.00%	76.00%
3PL [Member] \| Credit Concentration Risk [Member] \| Total Accounts Receivable [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage		93.00%

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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