Other Financial Data (Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Cost Basis	$ 462	$ 33
Unrealized Gains	6	70
Unrealized Loss	(11)
Investments	457	103
Other investments, at cost	203	191
Equity method investments	9	22
Investments, Cost Basis	674	246
Investments	669	316
Less: current portion of available-for-sale securities	401	0
Long-term investments noncurrent	268	316
Government, agency, and government-sponsored enterprise obligations
Available-for-sale securities:
Cost Basis	455	14
Unrealized Gains	0	0
Unrealized Loss	(11)
Investments	444	14
Corporate bonds
Available-for-sale securities:
Cost Basis	7	16
Unrealized Gains	0	0
Unrealized Loss	0
Investments	7	16
Mutual funds
Available-for-sale securities:
Cost Basis		2
Unrealized Gains		0
Investments		2
Common stock and equivalents
Available-for-sale securities:
Cost Basis	0	1
Unrealized Gains	6	70
Unrealized Loss	0
Investments	$ 6	$ 71