Discontinued Operations - Schedule of Discontinued Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Costs and expenses:
Research and development expenses	$ 200		$ 200
Other income and expenses:
Gain on sale of commercial business			23,000
Income tax (expense) benefit	(6,500)		(6,500)
Total income from discontinued operations	16,330	$ 8,456	16,330	$ 547,994
Commercial Business [Member]
Revenues:
Product revenues, net				16,135
License and collaboration revenues				7,797
Other revenues				1,973
Total revenues				25,905
Costs and expenses:
Cost of revenues				3,890
Research and development expenses	171		171	3,730
Selling, general and administrative expenses				8,732
Restructuring expenses				9,535
Total costs and expenses	171		171	25,887
Other income and expenses:
Interest expense				(6,743)
Gain on sale of commercial business	23,000	3,497	23,000	601,670
Income from discontinued operations	22,829	3,497	22,829	594,945
Income tax (expense) benefit	(6,499)	4,959	(6,499)	(46,951)
Total income from discontinued operations	$ 16,330	$ 8,456	$ 16,330	$ 547,994