Assignment and License Agreements (Details) (USD $) In Millions, except Share data, unless otherwise specified			12 Months Ended	1 Months Ended			12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 1997 GlaxoSmithKline PLC (Glaxo)	Jun. 30, 2006 Supernus Pharmaceuticals, Inc.	Nov. 30, 2008 Eli Lilly and Company	Jul. 31, 2011 Toray	Dec. 31, 2007 Toray	Dec. 31, 2013 Toray	Dec. 31, 2011 Pluristem License Agreement	Aug. 31, 2011 Pluristem License Agreement
Assignment and License Agreements
Minimum term of royalty payment			10 years	12 years
Royalty as a percentage of net sales					5.00%
Milestone payment to be made upon commercial launch of Orenitram tablet				$ 2.0
Common stock issued (in shares)	63,013,192	62,082,007					400,000
Price per share (in dollars per share)							$ 27.21
Notice period							30 days
Non-refundable payments to be made under the license						50.0				7.0
Term of installment payments under license						5 years
Obligation and a corresponding charge to research and development expenses						46.3			5.0
Royalty payments, remaining obligation								$ 20.0