Noncontrolling Interests - Joint Ventures (Details)	3 Months Ended		12 Months Ended
	Sep. 30, 2018 entity	Apr. 01, 2018 entity	Dec. 30, 2018 restaurant entity	Dec. 31, 2017 restaurant entity
Minority Interest [Line Items]
Number of joint ventures			3	5
Joint ventures
Minority Interest [Line Items]
Number of joint ventures divested	1	1	2
Number of Restaurants | restaurant			183	246