Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Loss Contingencies [Line Items]
Other potential commitments	$ 10.0	$ 10.0
Termination effective date	Aug. 26, 2019
Maximum [Member]
Loss Contingencies [Line Items]
Commitment to make development and sales-related milestone payments	$ 30.0	$ 30.0

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.

No definition available.

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant