Restaurant Impairments, Closure Costs and Asset Disposals (Narrative) (Details) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2019 restaurant	Oct. 01, 2019 restaurant	Jan. 01, 2019 restaurant	Oct. 02, 2018 restaurant	Jul. 03, 2018 restaurant	Apr. 03, 2018 restaurant	Apr. 04, 2017 restaurant	Dec. 31, 2019 USD ($) restaurant	Jan. 01, 2019 USD ($) restaurant	Jan. 02, 2018 USD ($) restaurant
Restructuring and Related Activities [Abstract]
Number of restaurants impaired	0	0	0	0	0			2	1	34
Number of restaurants closed			7	3	7	2	55	5	19
Closure costs | $								$ (54)	$ 4,149	$ 20,052