Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2019 USD ($) Country State	Jul. 01, 2018 USD ($)	Dec. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Accounting Policies [Abstract]
Number of States in which Entity Operates | State	47
Number of foreign countries in which Entity operates | Country	14
Related Party Transaction [Line Items]
Restricted cash	$ 182,000	$ 207,000	$ 151,000
Deferred financing costs, net	883,000		$ 1,153,000
Cash, cash equivalents and restricted cash, at Carrying Value	113,818,000	89,094,000		$ 67,312,000
Contributions from franchisees to advertising and media funds	$ 1,700,000	$ 1,300,000