Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net loss	$ (1,177)	$ (534)
Basic weighted average shares outstanding (shares)	636	637
Dilutive effect of share-based awards (shares)	0	0
Diluted weighted average shares outstanding (shares)	636	637
Basic loss per share (USD per share)	$ (1.85)	$ (0.84)
Diluted loss per share (USD per share)	$ (1.85)	$ (0.84)