Other Operating Expenses (Income), net - Other Operating Expenses (Income), Net (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Net losses (gains) on disposal of assets, restaurant closures, and refranchisings	$ 3.0	$ 8.6	$ 9.7	$ 11.5
Litigation settlements (gains) and reserves, net	0.4	1.1	(5.7)	1.1
Net losses (gains) on foreign exchange	(32.6)	36.8	(16.2)	47.2
Other, net	(0.2)	0.3	(4.5)	0.8
Other operating expenses (income), net	$ (29.4)	$ 46.8	$ (16.7)	$ 60.6