Stockholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 10,003.1	$ 10,945.2
Amounts reclassified from AOCI	$ (2.0)	$ 0.1	24.6	6.2
Other comprehensive income, net of tax			66.8	37.9
Ending balance	7,451.3	11,204.9	7,451.3	11,204.9
Total AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(140.1)	(142.1)
AOCI activity before reclassification			42.2	31.7
Amounts reclassified from AOCI			24.6	6.2
Other comprehensive income, net of tax			66.8	37.9
Ending balance	(73.3)	(104.2)	(73.3)	(104.2)
Foreign currency translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(61.4)	(65.7)
AOCI activity before reclassification			28.4	11.6
Amounts reclassified from AOCI			26.2	4.7
Other comprehensive income, net of tax			54.6	16.3
Ending balance	(6.8)	(49.4)	(6.8)	(49.4)
Changes in benefit plan net gain (loss) and prior service (cost)/credit
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(65.3)	(69.3)
AOCI activity before reclassification			0.9	(0.2)
Amounts reclassified from AOCI			0.7	1.5
Other comprehensive income, net of tax			1.6	1.3
Ending balance	(63.7)	(68.0)	(63.7)	(68.0)
Unrealized net gains (losses) on available for sale securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(13.4)	(7.1)
AOCI activity before reclassification			12.9	20.3
Amounts reclassified from AOCI			(2.3)	0.0
Other comprehensive income, net of tax			10.6	20.3
Ending balance	$ (2.8)	$ 13.2	$ (2.8)	$ 13.2