Stock-Based Compensation - Valuation Assumptions Used to Estimate Grant-Date Fair Value (Details) |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 27, 2019 |
Sep. 28, 2018 |
Sep. 27, 2019 |
Sep. 28, 2018 |
|
Stock options | ||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
Risk-free interest rate | 1.57% | 2.91% | 1.82% | 2.83% |
Dividend yield | 0.00% | 0.00% | 0.00% | 0.00% |
Expected volatility | 48.00% | 55.00% | 48.00% | 55.00% |
Expected life | 4 years | 4 years 4 months 24 days | 4 years 4 months 24 days | 4 years 4 months 24 days |
ESPP | ||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
Risk-free interest rate | 2.09% | 2.11% | 2.34% | 1.74% |
Dividend yield | 0.00% | 0.00% | 0.00% | 0.00% |
Expected volatility | 43.00% | 51.00% | 52.00% | 52.00% |
Expected life | 6 months | 6 months | 6 months | 6 months |