Stockholders' Equity - Narrative - Employee Stock Purchase Plan (Details) - ESPP [Member] - Employee stock [Member] - shares shares in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Jan. 01, 2017 |
Jan. 03, 2016 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| ESPP number of shares reserved for issuance | 15.5 | ||
| Specified percentage of the fair market value of the common stock on the first or last day of the offering period whichever is lower at which stock is purchased | 85.00% | ||
| Total shares issued under the ESPP | 0.3 | 0.2 | 0.2 |
| Shares available for issuance | 14.0 | 14.3 | |