Earnings Per Share - Schedule of Computation for Earnings Per Share Types (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 946	$ 746
Basic weighted average shares outstanding, shares	774	818
Dilutive effect of share-based awards, shares	6	8
Diluted weighted average shares outstanding, shares	780	826
Basic earnings per share (in USD per share)	$ 1.22	$ 0.91
Diluted earnings per share (in USD per share)	$ 1.21	$ 0.90