New Accounting Standards (Summary of Adoption of ASU 2017-07) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
SG&A expenses									$ 2,627.5	$ 2,972.1	$ 3,231.0	$ 3,136.9
Operating profit	$ 1.3	$ 97.7	$ 30.5	$ (3.9)	$ (49.6)	$ 186.9	$ 53.0	$ 44.9	125.6	235.2	281.3	323.8
Other expense, net									(94.2)	7.1	34.6	172.9
Income before income taxes	$ (22.8)	$ 144.4	$ 21.3	$ (4.5)	$ (84.1)	$ 182.1	$ (0.3)	$ 10.4	$ 138.4	$ 108.1	120.7	31.2
As originally reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
SG&A expenses											3,239.0	3,138.8
Operating profit											273.3	321.9
Other expense, net											26.6	171.0
Income before income taxes											120.7	31.2
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating profit											8.0	1.9
Accounting Standards Update 2017-07 | Impact of adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
SG&A expenses											(8.0)	(1.9)
Operating profit											8.0	1.9
Other expense, net											8.0	1.9
Income before income taxes											$ 0.0	$ 0.0