Other Financial Data (Investments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments
Investments	$ 316	$ 232
Unrealized Gains	70
Cost Basis	246
Available-For-Sale Securities
Investments
Investments	103	35
Unrealized Gains	70
Cost Basis	33
Government, agency and government-sponsored enterprise obligations
Investments
Investments	14	15
Unrealized Gains	0
Cost Basis	14
Corporate bonds
Investments
Investments	16	7
Unrealized Gains	0
Cost Basis	16
Mutual funds
Investments
Investments	2	11
Unrealized Gains	0
Cost Basis	2
Common stock and equivalents
Investments
Investments	71	2
Unrealized Gains	70
Cost Basis	1
Other investments, at cost
Investments
Investments	191	182
Unrealized Gains	0
Cost Basis	191
Equity method investments
Investments
Investments	22	15
Unrealized Gains	0
Cost Basis	$ 22