Other Financial Data (Investments) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Cost Basis	$ 462	$ 56	$ 462
Unrealized Gains	6		6
Unrealized Loss	(11)		(11)
Investments	457	56	457
Other investments, at cost	203	211	203
Equity method investments	9	17	9
Cost Basis	674	284	674
Investments	669	284	669
Less: current portion of available-for-sale securities	438	46	438
Long-term investments noncurrent	231	238	231
Gains (losses) on sales of investments and businesses, net		(6)	107	$ 5
Investment impairments		4	6	$ 0
Government, agency, and government-sponsored enterprise obligations
Available-for-sale securities:
Cost Basis	455	51	455
Unrealized Gains	0		0
Unrealized Loss	(11)		(11)
Investments	444	51	444
Corporate bonds
Available-for-sale securities:
Cost Basis	7	5	7
Unrealized Gains	0		0
Unrealized Loss	0		0
Investments	7	5	7
Common stock and equivalents
Available-for-sale securities:
Cost Basis	0		0
Unrealized Gains	6		6
Unrealized Loss	0		0
Investments	6		6
Foreign Government Debt Securities
Available-for-sale securities:
Unrealized Loss	(11)		$ (11)
Payments to acquire United Kingdom treasury securities	$ 401
Gross realized gain (loss)		$ (19)