Fair Value Measurements (Schedule of Carrying Values and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Document Period End Date	Dec. 31, 2019
Carrying Value	$ 170	$ 164
Equity Securities, FV-NI and without Readily Determinable Fair Value	0	0
Insurance contracts in nonqualified pension trusts, carrying amount	35	37
Insurance contracts in nonqualified pension trusts, fair value	35	37
Long-term debt, including current installments of long-term debt, carrying amount	3,455	3,355
Long-term debt, including current installments of long-term debt, fair value	3,599	3,372
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Securities, FV-NI and without Readily Determinable Fair Value	0	0
Insurance contracts in nonqualified pension trusts, fair value	35	37
Long-term debt, including current installments of long-term debt, fair value	3,456	3,204
Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Securities, FV-NI and without Readily Determinable Fair Value	0	0
Insurance contracts in nonqualified pension trusts, fair value	0	0
Long-term debt, including current installments of long-term debt, fair value	$ 143	$ 168