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) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Fair value assets reconciliation of changes
Balance at the end of the period	$ 5,681
Auction rate securities
Fair value assets reconciliation of changes
Balance at the beginning of the period	5,196	$ 7,126
Settlements		(2,000)
Gain included in other comprehensive income (loss)	485	70
Balance at the end of the period	$ 5,681	$ 5,196