Other Financial Data (Investments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments
Short-term Investments	$ 2	$ 2
Investments	144	166
Unrealized Gains	3	2
Unrealized Losses	0	(1)
Cost Basis	143	167
Available-For-Sale Securities [Member]
Investments
Short-term Investments	2	2
Investments	38	39
Unrealized Gains	3	2
Unrealized Losses	0	(1)
Cost Basis	37	40
U.S. Government, Agency and Government-sponsored Enterprise Obligations
Investments
Short-term Investments	0	0
Investments	15	16
Unrealized Gains	0	0
Unrealized Losses	0	0
Cost Basis	15	16
Corporate Bonds
Investments
Short-term Investments	2	2
Investments	11	10
Unrealized Gains	0	0
Unrealized Losses	0	0
Cost Basis	13	12
Mortgage-backed Securities
Investments
Short-term Investments	0	0
Investments	2	2
Unrealized Gains	0	0
Unrealized Losses	0	0
Cost Basis	2	2
Common Stock and Equivalents
Investments
Short-term Investments	0	0
Investments	10	11
Unrealized Gains	3	2
Unrealized Losses	0	(1)
Cost Basis	7	10
Other Securities, At Cost
Investments
Short-term Investments	0	0
Investments	93	106
Unrealized Gains	0	0
Unrealized Losses	0	0
Cost Basis	93	106
Equity Method Investments
Investments
Short-term Investments	0	0
Investments	13	21
Unrealized Gains	0	0
Unrealized Losses	0	0
Cost Basis	$ 13	$ 21