Warranty Obligations (Tables)
 3 Months Ended
Apr. 01, 2018
Product Warranties Disclosures [Abstract]  
Changes in Warranty Obligations
The changes in the warranty obligation were as follows (in thousands):
Balance as of December 31, 2017
$
4,701

Provisions for warranties issued during the period
697

Fulfillment of warranty obligations
(802
)
Foreign exchange rate changes
116

Balance as of April 1, 2018
$
4,712