Leases - Future Minimum Lease Payments, Lessor Operating Leases, and Lease Guarantees (Details) $ in Millions	3 Months Ended
	Mar. 29, 2020 USD ($) lease restaurant	Mar. 31, 2019 USD ($)
Leases
sublease income	$ 2.5	$ 2.3
Number of domestic leases for which the Company is contingently liable | lease	113
Estimated maximum amount of undiscounted payments in the event of nonpayment by primary lessees	$ 17.9
United Kingdom franchise-owned restaurants
Leases
Number of units leased and subleased | restaurant	370
Initial lease terms on franchised sites	15 years