Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
NUMERATOR:
Net income	$ 733	$ 743	$ 1,195	$ 1,082
DENOMINATOR:
Weighted-average shares outstanding, basic	578	604	582	608
Dilutive effect of Employee stock options and restricted stock units	1	1	1	2
Adjusted weighted-average shares outstanding, diluted	579	605	583	610
NET INCOME PER SHARE:
Basic	$ 1.27	$ 1.23	$ 2.05	$ 1.78
Diluted	$ 1.27	$ 1.23	$ 2.05	$ 1.77
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1	0	1	0