Marketable Securities Composition (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Term of maturities of investments considered short-term	2 years
Short-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Maturing within one year	$ 9,515	$ 10,308
Maturing between one and two years	2,482	0
Total marketable securities	11,997	10,308
Corporate and government bonds and notes, and commercial paper | Short-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	11,909	10,230
Certificates of deposit | Short-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	$ 88	$ 78