Fair Value Measurements (Schedule of Carrying Values and Fair Values of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost investments, carrying amount	$ 145	$ 145
Cost investments, fair value	0	0
Insurance contracts in nonqualified trusts, carrying amount	57	62
Insurance contracts in nonqualified trusts, fair value	57	62
Long-term debt, including current installments of long-term debt, carrying amount	2,904	2,911
Long-term debt, including current installments of long-term debt, fair value	2,964	2,960
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	57	62
Long-term debt, including current installments of long-term debt, fair value	2,704	2,696
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	$ 260	$ 264