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, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 16
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	32	$ 30	$ 30
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	$ 8	$ 13
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.30%	2.80%
Rate of compensation increase	5.80%	5.50%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	2.80%	2.90%	4.20%
Expected long-term return on plan assets	4.10%	4.20%	5.30%
Rate of compensation increase	5.50%	4.80%	5.40%