Segment Reporting - Net Product Revenues by Product Category (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Net product revenues	$ 375,540	$ 235,441	$ 778,519	$ 438,042
Xifaxan [Member]
Segment Reporting Information [Line Items]
Net product revenues	133,590	150,587	256,925	303,872
Inflammatory Bowel Disease - Apriso/Uceris/Giazo/Colazal [Member]
Segment Reporting Information [Line Items]
Net product revenues	70,095	45,146	147,073	63,606
Diabetes - Glumetza and Cycloset [Member]
Segment Reporting Information [Line Items]
Net product revenues	110,749		250,632
Purgatives-OsmoPrep/MoviPrep
Segment Reporting Information [Line Items]
Net product revenues	9,053	20,814	16,667	34,876
Zegerid [Member]
Segment Reporting Information [Line Items]
Net product revenues	27,251		64,757
Other - Fenoglide/Anusol/Azasan/Diuril/Pepcid/Proctocort/Relistor/Deflux/Solesta/Fulyzaq/Metozolv [Member]
Segment Reporting Information [Line Items]
Net product revenues	$ 24,802	$ 18,894	$ 42,465	$ 35,688