Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative									$ 320.6	$ 275.2	$ 267.6
Other (income) expense									(3.4)	(2.4)	(56.1)
Total	$ (21.1)	$ (18.6)	$ 49.8	$ 54.3	$ 7.4	$ (6.7)	$ 2.7	$ 1.5	64.4	4.9	(156.9)
Tax expense (benefit)									(224.7)	14.8	45.6
Total reclassifications for the period	$ (214.3)	$ (12.8)	$ 27.6	$ 39.2	$ 13.2	$ (3.0)	$ 8.0	$ 1.5	(160.3)	19.7	(111.3)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total									2.3	1.4	(41.1)
Tax expense (benefit)									(1.2)	(0.5)	(0.2)
Total reclassifications for the period									1.1	0.9	(41.3)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of actuarial losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative									1.4	1.4	0.3
Reclassification out of Accumulated Other Comprehensive Income | Settlement loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative									0.9	0.0	0.2
Reclassification out of Accumulated Other Comprehensive Income | Reclassification of foreign currency items to other (income) expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (income) expense									$ 0.0	$ 0.0	$ (41.6)