Loss Per Share - Computation of Basic and Diluted Earnings 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]
Loss available to common stockholders	$ (1,357)	$ (1,704)
Weighted-average shares outstanding, basic and diluted (in shares)	316.6	248.5
Loss per share, basic and diluted (in dollars per share)	$ (4.29)	$ (6.86)