Fair Value Measurements (Schedule of Carrying Values and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost investments, carrying amount	$ 147	$ 145
Cost investments, fair value	0	0
Insurance contracts in nonqualified trusts, carrying amount	48	56
Insurance contracts in nonqualified trusts, fair value	48	56
Long-term debt, including current installments of long-term debt, carrying amount	2,567	2,633
Long-term debt, including current installments of long-term debt, fair value	2,548	2,658
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost investments, fair value	0	0
Insurance contracts in nonqualified trusts, fair value	48	56
Long-term debt, including current installments of long-term debt, fair value	2,301	2,398
Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost investments, fair value	0	0
Insurance contracts in nonqualified trusts, fair value	0	0
Long-term debt, including current installments of long-term debt, fair value	$ 247	$ 260