Acquisitions, Divestitures and Other Arrangements - Loss on Sale of Assets (Detail) - Disposal Group, Not Discontinued Operations [Member] - MIGERGOT Transaction [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash proceeds	$ 6,000
Less net assets sold:
Developed technology	(16,999)
Inventory	(236)
Release of contingent consideration liability	272
Loss on sale of assets	$ (10,963)