Discontinued Operations - Sale of Commercial Business - Schedule of Discontinued Operations and Assets Held for Sale (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other income and expenses:
Income tax expense									$ (46,600)	$ (13,200)	$ (11,200)
Total income from discontinued operations	$ 1,122	$ (8,456)	$ (540,485)	$ 947	$ (6,464)	$ 3,430	$ (675)	$ 943	546,872	2,766	3,832
Commercial Business [Member]
Revenues:
Product revenues, net									16,135	53,064	4,328
License and collaboration revenues									7,797	87,119	84,930
Other revenues									1,973	4,090
Total revenues									25,905	144,273	89,258
Costs and expenses:
Cost of revenues									3,890	6,912	46
Research and development expenses									3,002	51,352	39,955
Selling, general and administrative expenses									10,907	48,677	33,747
Restructuring expenses									9,535	146
Total costs and expenses									27,334	107,087	73,748
Other income and expenses:
Interest expense									(6,743)	(21,196)	(463)
Gain on sale of Commercial Business									601,670
Income from discontinued operations									593,498	15,990	15,047
Income tax expense									(46,626)	(13,224)	(11,215)
Total income from discontinued operations									$ 546,872	$ 2,766	$ 3,832