(Loss)/Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net (loss)/income	$ (12,385)	$ 4,767	$ 3,935
Basic weighted average shares outstanding (shares)	636	651	691
Dilutive effect of share-based awards (shares)	0	2	3
Diluted weighted average shares outstanding (shares)	636	653	694
Basic (loss) earnings per share (usd per share)	$ (19.49)	$ 7.32	$ 5.69
Diluted (loss) earnings per share (usd per share)	$ (19.49)	$ 7.30	$ 5.67