Retirement Benefits (Net Amount Included In Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 212	$ 134
Current liabilities	(6)	(6)
Noncurrent liabilities	(60)	(53)
Net amount at December 31	146	75
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0	0
Current liabilities	0	0
Noncurrent liabilities	(56)	(95)
Net amount at December 31	$ (56)	$ (95)