Net Loss per Share - Anti-dilutive Securities (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Anti-Dilutive Securities
Anti-dilutive securities (in shares)	15,576	14,739	14,983	13,242
Share issuances under equity incentive plans and ESPP
Anti-Dilutive Securities
Anti-dilutive securities (in shares)	8,900	8,063	8,307	6,566
Share issuances upon the conversion of convertible senior notes
Anti-Dilutive Securities
Anti-dilutive securities (in shares)	6,676	6,676	6,676	6,676

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration