Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Changes in the carrying amount of goodwill
Balance at the beginning of the period, Goodwill gross	$ 151,181
Goodwill adjustments related to acquisitions	12,831
Effect of foreign currency translation	181
Balance at the end of the period, Goodwill gross	164,193
Balance at the beginning of the period, Accumulated impairment losses	(76,417)
Balance at the end of the period, Accumulated impairment losses	(76,417)
Balance at the beginning of the period, Goodwill, net	74,764
Balance at the end of the period, Goodwill, net	87,776
Intangible assets impairment losses	$ 0	$ 0