Guarantees and Other Commitments and Contingencies Franchisee Image Activation Incentive Programs (Details) - Maximum	9 Months Ended
	Sep. 30, 2018
New Build Incentive Program
Guarantor Obligations
Years of reduction in royalty payment attributable to new builds	2 years
2018 New Build Incentive Program
Guarantor Obligations
Years of reduction in royalty payment attributable to new builds	2 years
Remodel Incentive Program
Guarantor Obligations
Years of reduction in royalty payment attributable to remodel incentive program	1 year