Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended		1 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Jul. 31, 2010 Corporate headquarters item sqft	Mar. 31, 2013 Corporate headquarters sqft	Nov. 30, 2011 South San Francisco California item sqft	Mar. 31, 2013 South San Francisco California
Operating Leased Assets
Commitment to purchase products and services	$ 10.0
Leased space			126,493	107,000	170,618
Number of renewal options			2		2
Lease renewal terms			5 years		5 years
Number of options to lease additional premises					1
Term of lease automatically extended in case option exercised						10 years
Rent expense, net of sublease income	3.6	1.1
Sublease income	$ 0	$ 0