Other Comprehensive Income (Loss) (AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ 2,699.1
Other comprehensive income (loss) before reclassifications	$ 114.1	$ 37.1	(328.7)	$ (43.6)
Net amount reclassified from accumulated other comprehensive loss	88.9	49.9	169.4	183.3
Net other comprehensive income (loss)	203.0	87.0	(159.3)	139.7
Balance at end of period	4,272.0		4,272.0
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(6,885.9)	(5,687.5)	(6,523.6)	(5,740.2)
Balance at end of period	(6,682.9)	(5,600.5)	(6,682.9)	(5,600.5)
Foreign Currency Translation Gains (Losses)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(1,804.5)	(1,601.4)
Other comprehensive income (loss) before reclassifications	82.0	31.4
Net amount reclassified from accumulated other comprehensive loss	0.0	0.0
Net other comprehensive income (loss)	82.0	31.4
Balance at end of period	(1,722.5)	(1,570.0)	(1,722.5)	(1,570.0)
Unrealized Net Gains (Losses) on Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	5.8	(3.6)
Other comprehensive income (loss) before reclassifications	5.8	8.4
Net amount reclassified from accumulated other comprehensive loss	3.5	(0.3)
Net other comprehensive income (loss)	9.3	8.1
Balance at end of period	15.1	4.5	15.1	4.5
Defined Benefit Pension and Retiree Health Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(4,530.3)	(3,813.7)
Other comprehensive income (loss) before reclassifications	(6.7)	3.4
Net amount reclassified from accumulated other comprehensive loss	82.1	47.0
Net other comprehensive income (loss)	75.4	50.4
Balance at end of period	(4,454.9)	(3,763.3)	(4,454.9)	(3,763.3)
Effective Portion of Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(556.9)	(268.8)
Other comprehensive income (loss) before reclassifications	33.0	(6.1)
Net amount reclassified from accumulated other comprehensive loss	3.3	3.2
Net other comprehensive income (loss)	36.3	(2.9)
Balance at end of period	(520.6)	(271.7)	(520.6)	(271.7)
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(6,885.9)	(5,687.5)	(6,523.6)	(5,729.2)
Balance at end of period	(6,682.9)	(5,600.5)	(6,682.9)	(5,600.5)
AOCI Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period				(11.0)
Continuing Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net other comprehensive income (loss)	203.0	87.0	(159.3)	82.9
Continuing Operations | Foreign Currency Translation Gains (Losses)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(1,678.0)	(1,569.7)
Other comprehensive income (loss) before reclassifications			(44.5)	(0.3)
Net amount reclassified from accumulated other comprehensive loss			0.0	0.0
Net other comprehensive income (loss)			(44.5)	(0.3)
Balance at end of period	(1,722.5)	(1,570.0)	(1,722.5)	(1,570.0)
Continuing Operations | Unrealized Net Gains (Losses) on Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			4.9	(22.1)
Other comprehensive income (loss) before reclassifications			6.8	25.2
Net amount reclassified from accumulated other comprehensive loss			3.4	1.4
Net other comprehensive income (loss)			10.2	26.6
Balance at end of period	15.1	4.5	15.1	4.5
Continuing Operations | Defined Benefit Pension and Retiree Health Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(4,638.6)	(3,852.7)
Other comprehensive income (loss) before reclassifications			24.2	(2.3)
Net amount reclassified from accumulated other comprehensive loss			159.5	91.7
Net other comprehensive income (loss)			183.7	89.4
Balance at end of period	(4,454.9)	(3,763.3)	(4,454.9)	(3,763.3)
Continuing Operations | Effective Portion of Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(211.9)	(238.9)
Other comprehensive income (loss) before reclassifications			(315.2)	(39.0)
Net amount reclassified from accumulated other comprehensive loss			6.5	6.2
Net other comprehensive income (loss)			(308.7)	(32.8)
Balance at end of period	(520.6)	(271.7)	(520.6)	(271.7)
Discontinued Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net other comprehensive income (loss)	0.0	0.0	0.0	56.8
Discontinued Operations | Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			0.0	(56.8)
Other comprehensive income (loss) before reclassifications			0.0	(27.2)
Net amount reclassified from accumulated other comprehensive loss			0.0	84.0
Net other comprehensive income (loss)			0.0	56.8
Balance at end of period	$ 0.0	$ 0.0	$ 0.0	$ 0.0