Commitments and Contingencies (Details) (USD $)	12 Months Ended			1 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jul. 31, 2010 Corporate headquarters sqft item	Nov. 30, 2011 South San Francisco California item sqft	Dec. 31, 2012 South San Francisco California
Operating Leased Assets
Leased space				126,493	170,618
Number of renewal options				2	2
Lease renewal terms				5 years	5 years
Term of lease automatically extended in case option exercised						10 years
Number of options to lease additional premises					1
Minimum annual rental commitments, net of sublease income:
2013	$ 10,797,000
2014	10,817,000
2015	9,883,000
2016	12,090,000
2017	12,540,000
Thereafter	71,472,000
Total	127,599,000
Other disclosure
Rent expense, net of sublease income	5,800,000	6,100,000	4,300,000
Sublease income	$ 0	$ 0	$ 66,000