Business and Summary of Significant Accounting Policies (Revenue Recognition) (Details) - restaurant	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019	Jan. 02, 2018
Franchisor Disclosure [Line Items]
Percent of gift cards expected to be unredeemed (percent)	9.00%
Gift card estimated redemption period	24 months
Franchise
Franchisor Disclosure [Line Items]
Number of restaurants	68	65	66
Number of restaurants opened during period	1	0	3
Number of company-owned restaurants acquired by franchisees	5