Collaborative, Licensing and Other Arrangements (Details)	12 Months Ended				12 Months Ended				12 Months Ended						12 Months Ended			12 Months Ended	1 Months Ended		12 Months Ended				3 Months Ended		1 Months Ended		12 Months Ended						1 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 License Arrangement [Member] License	Dec. 31, 2014 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 1 [Member] USD ($)	Dec. 31, 2013 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 1 [Member] USD ($)	Dec. 31, 2012 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 1 [Member] USD ($)	Oct. 31, 2011 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 1 [Member] USD ($)	Dec. 31, 2014 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Dec. 31, 2013 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Dec. 31, 2012 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Dec. 31, 2010 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Dec. 31, 2009 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Sep. 30, 2008 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 2 [Member] USD ($)	Dec. 31, 2014 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 3 [Member] USD ($)	Dec. 31, 2012 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 3 [Member] USD ($)	Jul. 31, 2006 National Institute of Allergy and Infectious Diseases "NIAID" [Member] Arrangement with Governmental Agency 3 [Member] USD ($)	Dec. 31, 2007 Pfizer Inc. [Member] License Arrangement [Member] USD ($)	Jan. 31, 2011 Collaborative Arrangement [Member] Servier [Member] USD ($)	Jan. 31, 2011 Collaborative Arrangement [Member] Servier [Member] EUR (€)	Dec. 31, 2014 Collaborative Arrangement [Member] Servier [Member] USD ($)	Dec. 31, 2013 Collaborative Arrangement [Member] Servier [Member] USD ($)	Dec. 31, 2012 Collaborative Arrangement [Member] Servier [Member] USD ($)	Dec. 31, 2014 Collaborative Arrangement [Member] Servier [Member] Sales And Development Milestones [Member] USD ($)	Sep. 30, 2010 Collaborative Arrangement [Member] Servier - U.S. Perindopril Franchise [Member] USD ($)	Dec. 31, 2014 Collaborative Arrangement [Member] Servier - U.S. Perindopril Franchise [Member] Product	Feb. 28, 2009 Collaborative Arrangement [Member] Takeda [Member]	Nov. 30, 2006 Collaborative Arrangement [Member] Takeda [Member]	Dec. 31, 2014 Collaborative Arrangement [Member] Takeda [Member] USD ($)	Dec. 31, 2013 Collaborative Arrangement [Member] Takeda [Member] USD ($)	Dec. 31, 2012 Collaborative Arrangement [Member] Takeda [Member] USD ($)	Dec. 31, 2014 Collaborative Arrangement [Member] Takeda [Member] Development Milestone [Member] USD ($)	Feb. 28, 2009 Collaborative Arrangement [Member] Takeda [Member] Sales Milestone [Member] USD ($)	Nov. 30, 2006 Collaborative Arrangement [Member] Takeda [Member] Sales Milestone [Member] USD ($)	Jan. 31, 2014 Collaborative Arrangement [Member] Novartis [Member] USD ($)	Nov. 30, 2008 Collaborative Arrangement [Member] Novartis [Member] USD ($)	Dec. 31, 2014 Collaborative Arrangement [Member] Novartis [Member] USD ($)	Dec. 31, 2013 Collaborative Arrangement [Member] Novartis [Member] USD ($)	Nov. 30, 2008 Collaborative Arrangement [Member] Novartis [Member] Development Milestone [Member] USD ($) Product	Dec. 31, 2014 Collaborative Arrangement [Member] Pfizer Inc. [Member] Sales Milestone [Member] USD ($)	Dec. 31, 2012 Non-arrangement Transactions [Member] Pfizer Inc. [Member] Development Milestone [Member] USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment received																			$ 15,000,000
Period for recognizing deferred revenue																					8 months
Proceeds from loan																			19,500,000	15,000,000
Total contract amount awarded								28,000,000						64,800,000			16,300,000
Contractual term					5 years				3 years						3 years
Deferred revenue	1,939,000	4,105,000													1,900,000
Increase (decrease) in deferred revenue												900,000	1,100,000		(1,800,000)	2,000,000
Recognition of deferred revenue					8,400,000	4,700,000	2,500,000		1,200,000	4,400,000	6,600,000					2,000,000													1,600,000	100,000	1,200,000
Remaining deferred revenue															100,000
Future initial research and development expenses to be funded by counterparty																					50,000,000
Future other expenses to be funded by counterparty (in hundredths)																					50.00%
Licensing and collaboration agreement revenue	5,683,000	11,028,000	5,727,000																		3,500,000	13,600,000	14,500,000
Future milestone payments, maximum																								433,000,000									3,250,000	19,000,000					14,000,000
Future milestone payments, repurchase option not exercised, maximum																								770,000,000
Number of fixed-dose combination product candidates included in a portfolio of antihypertensive products from Servier																										3
License fees paid																									1,500,000
Future milestone payments with each additional future qualifying product candidate development, maximum																																20,750,000									1,700,000
Royalty right expiration period																											10 years	13 years 6 months								20 years
Proceeds from collaborators																																				6,200,000
Reduction in debt under restructured agreement																																				7,500,000
Number of ongoing product programs with potential royalty right milestone payments																																							2
Maximum borrowing capacity under agreement																																					50,000,000
Research and development expenses funded through loan facility, maximum (in hundredths)																																					75.00%
Additional future milestone payments																																								17,900,000
Number of licenses granted, minimum				60
Proceeds from license fees received																		30,000,000
Percentage of milestone received																																			25.00%
Milestone received under the collaboration agreement																																						7,000,000
Repayment of debt																																			$ 1,750,000
Euro to US Dollar exchange rates	1.216