Earnings Per Share - Schedule of Computation for Earnings Per Share Types (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 1,495	$ 1,443	$ 730	$ 1,322	$ 1,036	$ 557	$ 3,669	$ 2,916
Basic weighted average shares outstanding (shares)	646			686			654	695
Dilutive effect of share-based awards (shares)	2			2			2	2
Diluted weighted average shares outstanding (shares)	648			688			656	697
Basic earnings per share (USD per share)	$ 2.32			$ 1.93			$ 5.61	$ 4.20
Diluted earnings per share (USD per share)	$ 2.31			$ 1.92			$ 5.59	$ 4.18