Leases - Future Minimum Lease Payments, Lessor Operating Leases, and Lease Guarantees (Details) $ in Millions	3 Months Ended
	Mar. 28, 2021 USD ($) restaurant lease	Mar. 29, 2020 USD ($)
Leases
sublease income	$ 2.8	$ 2.5
Number of domestic leases for which the Company is contingently liable | lease	80
Estimated maximum amount of undiscounted payments in the event of nonpayment by primary lessees	$ 13.6
United Kingdom franchise-owned restaurants
Leases
Number of units leased and subleased | restaurant	390
Initial lease terms on franchised sites	15 years