Retirement Plans (Retirement Plans, Net Periodic Benefit Cost, Assumptions, and Expected Cash Flows) (Details) - Foreign Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 17
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 30	$ 23	$ 32
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	1.80%	2.50%
Rate of compensation increase	5.90%	6.00%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	2.50%	3.30%	2.80%
Expected long-term return on plan assets	3.50%	4.40%	4.10%
Rate of compensation increase	6.00%	5.80%	5.50%