Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

License Agreements and Acquired Product Rights - Additional Information (Detail) $ in Millions, $ in Millions	1 Months Ended		9 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2018 CAD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Collaborative Arrangement, Product [Member] \| Purdue Pharma [Member] \| BELBUCA [Member]
Indefinite-lived Intangible Assets [Line Items]
Milestone based payments received	$ 0.8	$ 1.0
TTY License and Supply Agreement [Member]
Indefinite-lived Intangible Assets [Line Items]
Milestone payment received			$ 0.9	$ 0.9