Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands |
Sep. 28, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Contract compliance | ||
| Loss Contingencies [Line Items] | ||
| Contracts loss contingency accrual | $ 8,500 | $ 5,800 |
| Pending Litigation | Class Action Employment Suit | ||
| Loss Contingencies [Line Items] | ||
| Estimate of possible loss, settlement fund (up to) | $ 3,750 |