Fair Value Measurements - Liabilities Measured at Fair Value on Recurring Basis Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration at December 31, 2018	$ 132,834
Changes in fair value of other contingent consideration	19,916
Milestone payments to Ares Trading S.A. (Merck Serono)	(83,472)
Milestone payments to former LEAD Therapeutics, Inc. shareholders	(5,987)
Realized gain on settlement of contingent consideration	(1,928)
Foreign exchange remeasurement of Euro denominated contingent consideration	(2,433)
Contingent consideration at September 30, 2019	$ 58,930

Fair value measurement with unobservable inputs reconciliations recurring basis foreign exchange remeasurement.

No definition available.

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- Definition

Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Milestone Payments To Ares Trading S.A.

+ References

No definition available.

+ Details

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- Definition

Fair value measurement with unobservable inputs reconciliations recurring basis milestone payments to shareholders.

+ References

No definition available.

+ Details

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- Definition

Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Realized Gain on Settlement of Contingent Consideration

+ References

No definition available.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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