Fair Values of Financial Assets and Liabilities (Details) - Fair Value Measurements Recurring - USD ($) $ in Thousands	Jun. 29, 2018	Dec. 31, 2017
Assets
Cash equivalents	$ 2,987	$ 2,665
Assets, fair value	2,996	2,815
Liabilities
Liabilities, fair value	2,474	4,104
Prepaid Expenses and Other Current Assets
Assets
Foreign currency forward contracts	9	150
Other Liabilities
Liabilities
Contingent consideration - Long-term	2,438	1,304
Accrued Expenses And Other Current Liabilities
Liabilities
Foreign currency forward contracts	36
Contingent consideration - Current		2,800
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash equivalents	2,987	2,665
Assets, fair value	2,987	2,665
Significant Other Observable Inputs (Level 2)
Assets
Assets, fair value	9	150
Liabilities
Liabilities, fair value	36
Significant Other Observable Inputs (Level 2) | Prepaid Expenses and Other Current Assets
Assets
Foreign currency forward contracts	9	150
Significant Other Observable Inputs (Level 2) | Accrued Expenses And Other Current Liabilities
Liabilities
Foreign currency forward contracts	36
Significant Other Unobservable Inputs (Level 3)
Liabilities
Liabilities, fair value	2,438	4,104
Significant Other Unobservable Inputs (Level 3) | Other Liabilities
Liabilities
Contingent consideration - Long-term	$ 2,438	1,304
Significant Other Unobservable Inputs (Level 3) | Accrued Expenses And Other Current Liabilities
Liabilities
Contingent consideration - Current		$ 2,800