Organization and Summary of Significant Accounting Policies - Narrative - Concentrations of Risk (Details) |
12 Months Ended | ||||
|---|---|---|---|---|---|
Dec. 31, 2017 |
Jan. 01, 2017 |
Dec. 31, 2017 |
Jan. 01, 2017 |
Jan. 03, 2016 |
|
| Credit concentration risk [Member] | Investment portfolio [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Maximum investment portfolio credit exposure | 5.00% | ||||
| Credit concentration risk [Member] | Issue size [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Maximum investment portfolio credit exposure | 5.00% | ||||
| Industry credit concentration risk [Member] | Investment portfolio [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Maximum investment portfolio credit exposure | 30.00% | ||||
| Geographic concentration risk [Member] | Sales revenue, net [Member] | Outside the United States [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Concentration percent | 45.00% | 46.00% | 46.00% | ||
| Geographic concentration risk [Member] | Accounts receivable [Member] | Outside the United States [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Concentration percent | 48.00% | 48.00% | |||