Derivatives - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 30, 2017
Designated as Hedging Instrument [Member] | Swap Agreement 2015 [Member] | Other Long-Term Assets [Member]
Derivatives in an Asset Position:
Derivatives in an asset position	$ 209	$ 126
Notional amount, Derivative asset	10,000	10,000
Designated as Hedging Instrument [Member] | Swap Agreement 2018 [Member] | Other Long-Term Liabilities [Member]
Derivatives in an Asset Position:
Derivatives in an asset position	(210)	0
Notional amount, Derivative asset	15,000	0
Not Designated as Hedging Instrument [Member] | Forward currency-exchange contracts [Member] | Other Current Assets [Member]
Derivatives in an Asset Position:
Derivatives in an asset position	0	17
Notional amount, Derivative asset	0	1,244
Not Designated as Hedging Instrument [Member] | Forward currency-exchange contracts [Member] | Other Current Liabilities [Member]
Derivatives in a Liability Position:
Derivatives in a liability position	(52)	(16)
Notional amount, Derivative liability	$ 2,712	$ 2,049