Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
NUMERATOR:
Net income	$ 615	$ 528	$ 1,811	$ 1,610
DENOMINATOR:
Weighted-average shares outstanding, basic	569	597	578	605
Dilutive effect of Employee stock options and restricted stock units	0	1	1	1
Adjusted weighted-average shares outstanding, diluted	569	598	579	606
NET INCOME PER SHARE:
Basic	$ 1.08	$ 0.88	$ 3.13	$ 2.66
Diluted	$ 1.08	$ 0.88	$ 3.13	$ 2.66