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Employee Stock Plans - Employee Stock Purchase Plan (Details) - 2009 ESPP - shares
3 Months Ended
Apr. 26, 2017
Apr. 23, 2015
Apr. 02, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Additional shares of common stock reserved for issuance (in shares)   1,000,000.0  
Shares reserved for issuance     3,300,000
Duration of offering period     6 months
Percentage of employee's total compensation     20.00%
Maximum number of shares per offering period (in shares)     20,000
Fair market value of common stock (as a percent)     85.00%
Subsequent event      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Additional shares of common stock reserved for issuance (in shares) 1,500,000.0