COLLABORATION AGREEMENTS (Details) (Collaborations, USD $)						3 Months Ended			12 Months Ended		12 Months Ended		3 Months Ended	0 Months Ended	3 Months Ended
	Mar. 30, 2012 Medicis	Mar. 30, 2012 Development and license agreement with a specialty pharmaceutical company	Feb. 09, 2011 Research and development agreement with Anacor	Sep. 10, 2010 Collaboration with a privately-held U.S. biotechnology company	Mar. 30, 2012 Joint development agreement with Lupin	Jun. 30, 2012 GlaxoSmithKline Ezogabine/retigabine	Jun. 30, 2011 GlaxoSmithKline Ezogabine/retigabine	Dec. 31, 2012 GlaxoSmithKline Ezogabine/retigabine	Dec. 31, 2012 GlaxoSmithKline TrobaltTM	May 31, 2011 GlaxoSmithKline TrobaltTM	Dec. 31, 2012 GlaxoSmithKline PotigaTM	Apr. 30, 2012 GlaxoSmithKline PotigaTM	Jun. 30, 2011 Meda Pharma GmbH & Co. KG (Meda Pharma) PotigaTM	Oct. 02, 2012 BMS Collaboration and Option Agreements	Dec. 31, 2012 BMS Collaboration and Option Agreements
Collaboration Agreement
GSK milestone payment, maximum percentage of royalty on net sales of product outside of the Collaboration Territory								20.00%	20.00%
GSK milestone payment, maximum percentage of royalty on net sales of backup compounds								20.00%
Milestone payments in terms of Collaboration Agreement								$ 545,000,000
Milestone payments received from GSK						45,000,000	40,000,000
Milestone payments in terms of Collaboration Agreement for products based on backup compounds								150,000,000
Minimum age limit for adjunctive treatment with epilepsy									18 years		18 years
GSK milestone payment										40,000,000		45,000,000
GSK milestone payment, maximum percentage of net profits shared on sales of product											50.00%
Milestone payment made													6,000,000
Term of additional rights														2 years
Consideration paid for rights															83,300,000
Potential contingent consideration payment	$ 80,000,000	$ 120,000,000	$ 153,000,000	$ 75,000,000	$ 35,500,000