Commitments and Contingencies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 CAD ($)	Oct. 23, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Other Commitments [Line Items]
Event of default, loan due In full, term	90 days
Portion that company might be obligated to repay in the event franchisees defaulted			$ 41.0
Fair value of franchisee-related borrowings			0.5
Loan facility to franchisees, maximum commitment amount			85.0
Loss contingency accrual			2.3	$ 7.3
Reserve for unfunded loan commitments			0.7	0.6
Unused credit card lines
Other Commitments [Line Items]
Remaining credit available			350.4	$ 354.5
Minimum
Other Commitments [Line Items]
Range of possible loss not accrued			0.0
Loss contingency, estimate of possible loss			3.0
Maximum
Other Commitments [Line Items]
Range of possible loss not accrued			1.0
Loss contingency, estimate of possible loss			$ 7.0
Franchise Loan Facility
Other Commitments [Line Items]
Loan facility maximum Canadian sub facility commitment amount	$ 25,000,000
Subsequent Event
Other Commitments [Line Items]
Loan facility to franchisees, maximum commitment amount		$ 55.0