Other Comprehensive Income (Loss) Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		$ 74.5
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax		27.7	$ 0.0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax	[1]	(15.4)	(19.1)
Accumulated other comprehensive loss		(4,264.7)	(4,657.5)	$ (4,580.7)	$ (3,991.8)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		200.4	(709.9)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, Net of Tax		115.6	44.2
Other comprehensive income (loss), net of tax		316.0	(665.7)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	[1]	73.5	101.8
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		58.1	82.7
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Tax		(23.0)	(29.0)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Net of Tax		35.1	53.7
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax		5.5	(18.3)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax		(1.9)	6.4
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		3.6	(11.9)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax		(4.2)	(30.0)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, before Reclassification Adjustments, Tax		(25.7)	(42.5)
Other Comprehensive Income, Other, Net of Tax	[2]	76.9	2.4
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax		(1.3)	18.5
Other Comprehensive Income (Loss), Tax		(3.5)	(54.0)
Accumulated Translation Adjustment [Member]
Accumulated other comprehensive loss		(1,085.4)	(1,294.4)	(1,360.2)	(498.4)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		200.3	(796.0)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, Net of Tax		74.5	0.0
Other comprehensive income (loss), net of tax		274.8	(796.0)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated other comprehensive loss		17.9	155.6	10.1	99.7
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		4.2	67.8
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, Net of Tax		3.6	(11.9)
Other comprehensive income (loss), net of tax		7.8	55.9
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive loss		(2,981.1)	(3,293.1)	(3,012.1)	(3,402.0)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		(4.1)	55.2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, Net of Tax		35.1	53.7
Other comprehensive income (loss), net of tax		31.0	108.9
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated other comprehensive loss		(216.1)	(225.6)	$ (218.5)	$ (191.1)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		0.0	(36.9)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, Net of Tax		2.4	2.4
Other comprehensive income (loss), net of tax		$ 2.4	$ (34.5)

[1] (1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit (income) cost (see Note 9).

[2] (2) Amount for the three months ended March 31, 2016 included primarily $74.5 million of foreign currency translation losses.