Industry and Geographic Information - Consolidated Net Product Revenues by Disease State (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 277,743	$ 191,603	$ 196,129
Infectious Disease [Member]
Segment Reporting Information [Line Items]
Revenues	165,099	121,416	130,348
Women's Health [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Gastrointestinal Disease [Member]
Segment Reporting Information [Line Items]
Revenues	51,978	60,681	60,358
Royalty, License Fees and Grant Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	$ 13,636	$ 9,506	$ 5,423