Retirement Benefits (Schedule of Benefit Obligations and Plan Assets and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets:
Accrued retirement benefits	$ (1,438.8)	$ (1,305.1)
Defined Benefit Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year	13,222.0	17,565.0
Service cost	290.4	351.7	$ 369.2
Interest cost	648.2	398.1	337.8
Actuarial (gain) loss	590.5	(4,158.9)
Benefits paid	(610.5)	(608.9)
Foreign currency exchange rate changes and other adjustments	117.3	(325.0)
Benefit obligation at end of year	14,257.9	13,222.0	17,565.0
Change in plan assets:
Fair value of plan assets at beginning of year	13,708.7	13,195.8	16,416.0
Actual return on plan assets	881.9	(2,388.1)
Employer contribution	120.6	118.1
Benefits paid	(610.5)	(608.9)
Foreign currency exchange rate changes and other adjustments	120.9	(341.3)
Fair value of plan assets at end of year	13,708.7	13,195.8	16,416.0
Funded status	(549.2)	(26.2)
Unrecognized net actuarial (gain) loss	3,357.9	2,687.2
Unrecognized prior service (benefit) cost	6.4	8.4
Net amount recognized	2,815.1	2,669.4
Other noncurrent assets	810.6	1,208.0
Other current liabilities	(70.4)	(70.4)
Accrued retirement benefits	(1,289.4)	(1,163.8)
Accumulated other comprehensive (income) loss before income taxes	3,364.3	2,695.6
Retiree Health Benefit Plans
Change in benefit obligation:
Benefit obligation at beginning of year	1,258.8	1,663.8
Service cost	31.8	46.6	49.2
Interest cost	61.3	37.8	32.5
Actuarial (gain) loss	34.5	(395.9)
Benefits paid	(80.6)	(86.8)
Foreign currency exchange rate changes and other adjustments	4.5	(6.7)
Benefit obligation at end of year	1,310.3	1,258.8	1,663.8
Change in plan assets:
Fair value of plan assets at beginning of year	2,580.3	2,492.5	3,361.4
Actual return on plan assets	166.8	(796.0)
Employer contribution	1.7	13.9
Benefits paid	(80.6)	(86.8)
Foreign currency exchange rate changes and other adjustments	(0.1)	0.0
Fair value of plan assets at end of year	2,580.3	2,492.5	$ 3,361.4
Funded status	1,270.0	1,233.7
Unrecognized net actuarial (gain) loss	109.6	54.5
Unrecognized prior service (benefit) cost	(9.5)	(62.2)
Net amount recognized	1,370.1	1,226.0
Other noncurrent assets	1,427.7	1,383.4
Other current liabilities	(8.3)	(8.4)
Accrued retirement benefits	(149.4)	(141.3)
Accumulated other comprehensive (income) loss before income taxes	$ 100.1	$ (7.7)