Stockholder's Equity (Reclassification out of Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification out of Accumulated Other Comprehensive Income
Revenue	$ 3,125.2	$ 3,388.0
Selling, general and administrative expense	(303.1)	(254.1)
Research and development expense	(41.1)	(43.4)
Other income (expense), net	(25.2)	63.5
Income before income taxes	140.7	36.6
Provision for income taxes	49.3	51.8
Net income (loss)	91.4	(15.2)
Amount Reclassified out of Accumulated Other Comprehensive Loss
Reclassification out of Accumulated Other Comprehensive Income
Amortization of actuarial gain (loss)	0.0	(0.5)
Amortization of prior service credit (cost)		(0.2)
Income before income taxes	0.0	(0.7)
Provision for income taxes	0.0	(0.2)
Net income (loss)	0.0	(0.5)
Amount Reclassified out of Accumulated Other Comprehensive Loss | Hedging | Foreign exchange contracts
Reclassification out of Accumulated Other Comprehensive Income
Revenue	2.5	(14.6)
Cost of sales	1.6	(0.1)
Selling, general and administrative expense	0.1	0.0
Research and development expense	0.0	(0.1)
Other income (expense), net	(4.6)	(28.4)
Provision for income taxes	(0.2)	(8.8)
Net income (loss)	$ (0.2)	$ (34.4)