Net Income Per Share - Potential Shares of Common Stock Not Included in the Computation of Diluted Net Income (Loss) Per Share (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares (in shares)	5,687	583	2,938	1,108
Outstanding stock options, unvested RSUs and ESPP contributions
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares (in shares)	5,687	583	2,938	1,108

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