Fair Value Measurements Footnote (details) - Financial Instruments - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Financial Instruments
Short-term securities	$ 5,128	$ 4,364
Fair Value [Member]
Financial Instruments
Short-term securities	5,128	4,364
Debt	7,623	7,522
Commercial paper amount	100	100
Fair Value [Member] | Level 1 [Member]
Financial Instruments
Short-term securities	1,943	1,283
Fair Value [Member] | Level 2 [Member]
Financial Instruments
Short-term securities	3,148	3,042
Debt	7,623	7,522
Commercial paper amount	100	100
Fair Value [Member] | Level 3 [Member]
Financial Instruments
Short-term securities	37	39
Carrying Value [Member]
Financial Instruments
Short-term securities	5,128	4,364
Debt	6,643	6,249
Commercial paper amount	$ 100	$ 100