Novartis Relationship (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended		2 Months Ended	3 Months Ended		9 Months Ended					3 Months Ended	1 Months Ended					3 Months Ended			9 Months Ended					1 Months Ended			3 Months Ended	9 Months Ended			3 Months Ended
	Jul. 31, 2012	Jul. 31, 2004	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	May 31, 2004	Sep. 30, 2012 Novartis Reimbursement [Member]	Nov. 30, 2011 Novartis [Member]	Oct. 31, 2011 Novartis [Member]	Apr. 30, 2011 Novartis [Member]	Jul. 31, 2004 Novartis [Member]	May 31, 2003 Novartis [Member]	Sep. 30, 2012 Novartis [Member]	Mar. 31, 2012 Novartis [Member]	Sep. 30, 2011 Novartis [Member]	Sep. 30, 2012 Novartis [Member] Person	Sep. 30, 2011 Novartis [Member]	Oct. 24, 2012 Novartis [Member]	Jul. 31, 2012 Novartis [Member]	Dec. 31, 2011 Novartis [Member]	Apr. 30, 2012 Novartis [Member] Chief financial officer [Member]	Mar. 31, 2012 Novartis [Member] Prior to amendment [Member]	Apr. 30, 2011 Novartis [Member] Prior to amendment [Member]	Sep. 30, 2012 Novartis Non-Exclusive License to Conduct Combination Trials [Member]	Sep. 30, 2012 Novartis Non-Exclusive License to Conduct Combination Trials [Member]	Jul. 31, 2012 Novartis Non-Exclusive License to Conduct Combination Trials [Member]	Jun. 30, 2012 Novartis Non-Exclusive License to Conduct Combination Trials [Member] Prior to execution of termination agreement [Member]	Sep. 30, 2012 Novartis Non-Exclusive License to Conduct Combination Trials [Member] Collaboration revenue related to the non-exclusive license [Member]
Novartis Relationship (Textual) [Abstract]
Percentage of outstanding capital stock from stockholders																	30.00%			30.00%
Deferred revenue, related party	$ 5,000,000		$ 4,900,000	$ 4,900,000		$ 4,900,000		$ 24,700,000															$ 117,200,000					$ 4,900,000	$ 4,900,000	$ 5,000,000	$ 24,700,000
Term, in years, through which royalties are payable to a related party																				ten years after the first commercial sale of a product
Reduced rate of royalty after the expiration of agreed upon term with related party																				one-half
Royalty revenue - related party																	400,000		1,200,000	2,900,000	3,400,000
Receivables from related party			1,376,000	1,376,000		1,376,000			1,157,000								7,800,000			7,800,000				1,200,000
Breach of termination agreement, maximum days to cure																				30 days
Negotiation obligation period for parties																				180 days
Percentage of common stock outstanding purchased by a related party at inception of collaboration agreement																54.00%
Cash received from purchase of capital stock outstanding by a related party at inception of collaboration																				255,000,000
Aggregate amount contingently payable to stockholders by related party																357,000,000
Minimum percentage of voting stock owned by related party to nominate for election as director at least two related party designees																		30.00%							35.00%
Minimum percentage of voting stock owned by related party to nominate for election as director at least one related party designee																	19.40%			19.40%			15.00%
Minimum number of related party designees to be nominated as directors for at least 30% of voting stock																				2
Minimum number of related party designees to be nominated as directors for at least 19.4% of voting stock																				1
Period for related party to purchase shares in connection with acquisition or in-licensing																				24 months
Percentage premium to the consideration per share paid by others for related party to purchase shares			10.00%	10.00%		10.00%
Amount of shares of common stock which were issuable by us prior to the termination by the related party of their stock subscription right															1.4
Shares issued to related party in exchange for termination of stock subscription rights															1.1
Common shares, par value			$ 0.001	$ 0.001		$ 0.001			$ 0.001	$ 0.001							$ 0.001			$ 0.001
Fair Value of the common stock issued at par value to related party in exchange of termination of stock subscription rights		15,400,000
Terms of a related party termination agreement						7 years																							7 years
Aggregate impact of related party's stock subscription rights	26,300,000
Deferred revenue portion of aggregate impact of related party's stock subscription rights	6,300,000
License fee revenue portion of aggregate impact of related party's stock subscription rights	20,000,000
Impact on additional paid-in capital as a result of related party's stock subscription rights	400,000		4,000,000		0	400,000	0
Impact on deferred revenue as a result of related party's stock subscription rights	100,000		0		0	900,000	0
Impact on license fee revenue as a result of related party's stock subscription rights	300,000		4,000,000		0	1,300,000	0
Minimum interest rate issuance of capital shares												31.00%		30.00%			31.00%			31.00%		25.00%
Shares issued to related party pursuant to a private placement agreement														1.8
Net proceeds from shares issued pursuant to under written offering under shelf registration statement and to related party pursuant to private placement agreement														60,200,000
Minimum percentage ownership of our common stock by related party to have option to license our development stage drug candidates																		0.30									0.40
Minimum percentage ownership of our common stock by related party for consent requirement of selection and appointment of CFO																		30.00%								40.00%
Percentage of issuance of common stock in connection with acquisition or in-licensing of technology in which our related party has the right to purchase, at par value, such number of shares as is required to maintain its percentage ownership																	5.00%			5.00%
The maximum proceeds allowed from the offer and sale of common stock under a universal shelf registration statement with the SEC													150,000,000
Shares issued pursuant to underwritten offering under shelf registration statement filed with the SEC												10.8		21.1
Underwritten offering net proceeds						190,505,000	55,169,000					65,800,000
Deferred revenue, related party, recognized				$ 19,700,000							$ 7,400,000						$ 300,000		$ 800,000	$ 1,900,000	$ 2,300,000							$ 19,700,000				$ 100,000
Minimum percentage of voting stock owned for director election																	0.00%			0.00%