Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Anti-dilutive securities
Anti-dilutive securities (in shares)	19,463	20,653	20,101	20,100
Stock options
Anti-dilutive securities
Anti-dilutive securities (in shares)	4,000		4,200
RSUs
Anti-dilutive securities
Anti-dilutive securities (in shares)	300		400
Unvested RSAs
Anti-dilutive securities
Anti-dilutive securities (in shares)	800		1,000
Outstanding options and awards granted under equity incentive plan and ESPP
Anti-dilutive securities
Anti-dilutive securities (in shares)	5,070	6,771	5,459	6,218
Unvested RSAs
Anti-dilutive securities
Anti-dilutive securities (in shares)	1,489	1,782	1,738	1,782
Shares issuable upon conversion of convertible subordinated notes
Anti-dilutive securities
Anti-dilutive securities (in shares)	12,904	12,100	12,904	12,100