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Significant Accounting Policies - Additional Information (Detail)	6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) Segment Customer	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2012 USD ($)
Significant Accounting Policies [Line Items]
Trade receivables, credit period	30 days
Number of operating segments | Segment	1
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%		5.40%
Derivative liability fair value assumptions, market yields	8.30%		6.70%
Embedded Derivative Financial Instruments | BioPharma Debt | Maximum
Significant Accounting Policies [Line Items]
Derivative liability fair value assumption, coupon rate	10.00%		10.80%
Derivative liability fair value assumptions, market yields	15.80%		15.80%
Embedded Derivative Financial Instruments | BioPharma Debt | Measurement Input, Expected Term | Minimum
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term	1 year		1 year 3 months 18 days
Embedded Derivative Financial Instruments | BioPharma Debt | Measurement Input, Expected Term | Maximum
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term	7 years 9 months 18 days		4 years
Long-term debt from royalty-bearing instrument
Significant Accounting Policies [Line Items]
Long-term debt, discount	$ 0		$ 0
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	24.00%	27.00%
Customer A | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	38.00%	33.00%
Customer B | Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	37.00%	31.00%
Customer B | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	32.00%	37.00%
Customer C | Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	29.00%	31.00%
Customer C | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	22.00%	22.00%

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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 as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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