Significant Accounting Policies - Noncontrolling Interests and Foreign Currency Translation (Details)		3 Months Ended		12 Months Ended
	Jun. 15, 2018 USD ($) restaurant	Sep. 30, 2018 entity	Apr. 01, 2018 entity	Dec. 30, 2018 USD ($) restaurant entity	Dec. 31, 2017 restaurant entity
Noncontrolling Interests
Number of joint ventures | entity				3	5
Stores in Beijing and Tianjin, China
Noncontrolling Interests
Number of restaurants divested	34			34
Reversal of accumulated other comprehensive income related to foreign currency translation | $	$ 1,300,000			$ 1,300,000
Reversal of deferred tax related to foreign currency translation | $				$ 300,000
Joint ventures
Noncontrolling Interests
Number of joint ventures divested | entity		1	1	2
Number of restaurants divested				62
Number of Restaurants				183	246