Commitments and Contingencies (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($) item	Jun. 30, 2020 USD ($) item restaurant	Dec. 31, 2019 USD ($)
Commitments and Contingencies
Estimated cost to complete capital project commitments (in dollars)	$ 133.2	$ 133.2	$ 119.0
Number of continuing construction of restaurants. | restaurant		14
Number of relocated restraurants resumed construction | restaurant		1
Estimated cost of completion		$ 29.3
Number of suppliers providing most of the company's beef | item	3	3
Lease Agreements
Commitments and Contingencies
Number of leases guarantees entity contingently liable | item		7
Lease Agreements | Maximum
Commitments and Contingencies
Contingently liable amount	$ 13.5	$ 13.5	$ 13.9