Description Of Business (Narrative) (Details) (USD $)	12 Months Ended		3 Months Ended			12 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2011 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2010 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2009 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2011 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2010 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2009 Collaborative Arrangement [Member] Astellas [Member]	Dec. 31, 2008 Collaborative Arrangement [Member] Pfizer [Member]	Dec. 31, 2011 Collaborative Arrangement [Member] Pfizer [Member]	Dec. 31, 2010 Collaborative Arrangement [Member] Pfizer [Member]	Dec. 31, 2009 Collaborative Arrangement [Member] Pfizer [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cumulative net losses	$ (250,291,000)	$ (211,450,000)
Development milestone payments, fourth quarter of 2010				10,000,000
Development milestone payments, second quarter of 2011			3,000,000
Non-refundable up-front payments					110,000,000				225,000,000
Development and commercialization cost sharing amount						$ 43,800,000	$ 34,600,000	$ 2,900,000		$ 12,400,000	$ 28,100,000	$ 19,700,000
Percentage of sales and medical forces used for marketing approval of MDV3100	50.00%					50.00%