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 $ in Thousands	3 Months Ended
	Apr. 01, 2017 USD ($)
Fair value assets reconciliation of changes
Balance at the beginning of the period	$ 5,196
Gain included in other comprehensive loss	61
Balance at the end of the period	$ 5,257