(Loss)/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, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net (loss)/income	$ (5,717)	$ (534)	$ 1,443	$ 730	$ (6,251)	$ 2,173
Basic weighted average shares outstanding (shares)	635		650		636	658
Dilutive effect of share-based awards (shares)	0		2		0	2
Diluted weighted average shares outstanding (shares)	635		652		636	660
Basic (loss)/earnings per share (USD per share)	$ (9.01)		$ 2.22		$ (9.83)	$ 3.30
Diluted (loss)/earnings per share (USD per share)	$ (9.01)		$ 2.21		$ (9.83)	$ 3.29