Revenues (Disaggregation of Revenues) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Sales by Company-operated restaurants	$ 2,511.0	$ 3,064.3	$ 7,641.5	$ 10,045.8
Revenues from franchised restaurants	2,858.4	2,690.3	8,220.7	7,434.4
Total revenues	5,369.4	5,754.6	15,862.2	17,480.2
United States
Disaggregation of Revenue [Line Items]
Sales by Company-operated restaurants	637.3	798.7	2,042.8	2,483.8
Revenues from franchised restaurants	1,292.7	1,224.6	3,715.6	3,516.9
Total revenues	1,930.0	2,023.3	5,758.4	6,000.7
International Lead Markets
Disaggregation of Revenue [Line Items]
Sales by Company-operated restaurants	992.3	1,076.3	3,022.1	3,038.9
Revenues from franchised restaurants	948.2	894.2	2,726.8	2,388.3
Total revenues	1,940.5	1,970.5	5,748.9	5,427.2
High Growth Markets
Disaggregation of Revenue [Line Items]
Sales by Company-operated restaurants	737.8	1,054.9	2,170.7	3,859.5
Revenues from franchised restaurants	302.4	267.2	855.7	679.0
Total revenues	1,040.2	1,322.1	3,026.4	4,538.5
Foundational Markets and Corporate
Disaggregation of Revenue [Line Items]
Sales by Company-operated restaurants	143.6	134.4	405.9	663.6
Revenues from franchised restaurants	315.1	304.3	922.6	850.2
Total revenues	$ 458.7	$ 438.7	$ 1,328.5	$ 1,513.8