Restaurant Impairment, Closure Costs and Asset Disposals - Narrative (Details) $ in Millions	3 Months Ended			6 Months Ended
	Jul. 02, 2019 USD ($) restaurant	Apr. 02, 2019 restaurant	Jul. 03, 2018 USD ($) restaurant	Jul. 02, 2019 USD ($)	Jul. 03, 2018 USD ($) restaurant
Property, Plant and Equipment Impairment or Disposal [Abstract]
Number of restaurants impaired during the comparable periods | restaurant	2	0	0		1
Impairment of restaurants	$ 2.2
Impairment closure costs	0.2			$ 0.1
Gain (loss) relating to assessment of operating lease terms	$ (0.1)			$ (0.4)
Closure costs			$ 1.5		$ 2.1
Number of restaurants closed | restaurant			7		9