Fair Value of Financial Instruments - Assets in Level 3 (Details) - Assets and liabilities measured at fair value on recurring basis - Significant Unobservable Inputs (Level 3) - Auction rate securities - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Oct. 01, 2016	Oct. 01, 2016
Fair value assets reconciliation of changes
Balance at the beginning of the period	$ 6,921	$ 7,126
Gain (loss) included in other comprehensive income (loss)	59	(146)
Balance at the end of the period	$ 6,980	$ 6,980