Financing Obligations (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2008 USD ($) term_extension_option	Dec. 31, 2020 monthly_payment	Dec. 31, 2017 USD ($) real_property	May 19, 2008 real_property
Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
2018			$ 4.9
2019			5.1
2020			5.6
2021			5.1
2022			5.2
Thereafter			55.4
Total minimum lease payments			81.3
Less: interest			(41.8)
Total financing obligations			39.5
Less: current portion			(0.3)
Long-term financing obligations			$ 39.2
Sale Leaseback Transaction Agreement for Properties
Sale Leaseback Transaction [Line Items]
Parcels of real property under sale leaseback transaction | real_property				181
Master Lease Agreement
Sale Leaseback Transaction [Line Items]
Parcels of real property under sale leaseback transaction | real_property			181
Gross proceeds of sale leaseback transaction	$ 337.2
Sale leaseback initial term	20 years
Number of options to extend initial leaseback term | term_extension_option	4
Extension period for options to extend sale leaseback initial term (in years)	5 years
Properties assigned to franchisee or released from lessor | real_property			155
Reduction in property and equipment and financing obligations as a result of sales transactions			$ 280.0
Forecast
Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Number of monthly obligation payments in fiscal year | monthly_payment		13