Earnings Per Share - Schedule of Computation for Earnings Per Share Types (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 1,443	$ 730	$ 1,036	$ 557	$ 2,173	$ 1,594
Basic weighted average shares outstanding (shares)	650		695		658	699
Dilutive effect of share-based awards (shares)	2		2		2	2
Diluted weighted average shares outstanding (shares)	652		697		660	701
Basic earnings per share (USD per share)	$ 2.22		$ 1.49		$ 3.30	$ 2.28
Diluted earnings per share (USD per share)	$ 2.21		$ 1.49		$ 3.29	$ 2.27