Cash and Investments - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Investments Debt And Equity Securities [Abstract]
Net realized gain and losses	$ 0.2	$ 0.2	$ 0.2
Investment maturity period, less than	2 years	2 years