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Schedule of Valuation Assumptions (Details)
3 Months Ended 6 Months Ended
Jun. 28, 2015
Jun. 29, 2014
Jun. 28, 2015
Jun. 29, 2014
Stock options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Expected term   6 years 4 years 9 months 11 days 6 years 2 months 9 days
Risk-free interest rate 0.00% 1.90% 1.40% 1.98%
Expected volatility 0.00% 55.70% 52.11% 55.10%
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Employee stock purchase plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Expected term 6 months 2 days 6 months 3 days 6 months 2 days 6 months 3 days
Risk-free interest rate 0.08% 0.05% 0.08% 0.05%
Expected volatility 51.54% 49.17% 51.54% 49.17%
Expected dividend yield 0.00% 0.00%   0.00%