Stockholders' Equity (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	$ 13,409.4
Other comprehensive income (loss)	13.4	$ 67.0
Ending balance	13,281.8
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(1,014.6)
Other comprehensive income (loss) before reclassifications, net of tax	0.8
Reclassification adjustment for net losses included in net income, net of tax	0.0
Other comprehensive income (loss)	0.8
Ending balance	(1,013.8)
Hedging
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	27.8
Other comprehensive income (loss) before reclassifications, net of tax	11.2
Reclassification adjustment for net losses included in net income, net of tax	0.2
Other comprehensive income (loss)	11.4
Ending balance	39.2
Defined Pension and Other Post-Retirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(16.9)
Other comprehensive income (loss) before reclassifications, net of tax	(0.4)
Reclassification adjustment for net losses included in net income, net of tax	0.0
Other comprehensive income (loss)	(0.4)
Ending balance	(17.3)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(1,003.7)
Other comprehensive income (loss) before reclassifications, net of tax	11.6
Reclassification adjustment for net losses included in net income, net of tax	0.2
Other comprehensive income (loss)	11.8
Ending balance	(991.9)
AOCI Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	0.6
Other comprehensive income (loss) before reclassifications, net of tax	1.6
Reclassification adjustment for net losses included in net income, net of tax	0.0
Other comprehensive income (loss)	1.6
Ending balance	$ 2.2