Cash and Investments - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Net realized gains on sale of securities	$ 1.4	$ 1.3	$ 0.5
Investment effective maturity period, less than	3 years	3 years

Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

No definition available.

Name:	us-gaap_MarketableSecuritiesRealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration