Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	4,804	3,939
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	4,328	3,572
RSU
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	470	351
ESPP
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	6	16

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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