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, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Costs and expenses:
Research and development expenses							$ 200
Other income and expenses:
Gain on sale of Commercial Business							28,000
Income tax expense							(7,600)	$ (46,600)
Total income from discontinued operations	$ (3,931)	$ (16,330)	$ 1,122	$ (8,456)	$ (540,485)	$ 947	20,261	546,872
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	3,002
Selling, general and administrative expenses								10,907
Restructuring expenses								9,535
Total costs and expenses							171	27,334
Other income and expenses:
Interest expense								(6,743)
Gain on sale of Commercial Business							28,000	601,670
Income from discontinued operations							27,829	593,498
Income tax expense							(7,568)	(46,626)
Total income from discontinued operations							$ 20,261	$ 546,872