Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
NUMERATOR:
Net income (loss)	$ 446	$ (1,157)	$ 909	$ (2,166)
DENOMINATOR:
Weighted-average shares outstanding, Basic (in shares)	592	590	591	556
Dilutive effects of convertible notes (in shares)	14	0	17	0
Dilutive effect of stock warrants (in shares)	1	0	1	0
Dilutive effect of restricted stock units (in shares)	0	0	1	0
Diluted (in shares)	607	590	610	556
NET INCOME (LOSS) PER SHARE:
BASIC (in USD per share)	$ 0.75	$ (1.96)	$ 1.54	$ (3.89)
DILUTED (in USD per share)	0.73	$ (1.96)	1.49	$ (3.89)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Initial conversion price (in USD per share)	$ 38.48		$ 38.48
Convertible Debt Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potentially dilutive amounts excluded from calculations (in shares)	0	5	0	2
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potentially dilutive amounts excluded from calculations (in shares)	0	1	0	1