Earnings (Loss) per Common Share - Computation of Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2020
Basic EPS:
Net income (loss)	$ 1,338	$ 10	$ 476	$ (1,635)	$ 1,348	$ (1,159)
Basic weighted average common shares outstanding (in shares)	653,602		650,346		652,801	649,925
Basic EPS (in dollars per share)	$ 2.05		$ 0.73		$ 2.06	$ (1.78)
Diluted EPS:
Interest expense on 6.50% convertible senior notes	$ 12		$ 11		$ 23
Net income (loss) for purposes of computing diluted EPS	$ 1,350		$ 487		$ 1,371	$ (1,159)
Dilutive effect of stock awards (in shares)	1,307		1,477		1,185	0
Dilutive effect of warrants (in shares)	2,708		4,981		3,176	0
Assumed conversion of 6.50% convertible senior notes (in shares)	61,728		61,728		61,728	0
Diluted weighted average common shares outstanding (in shares)	719,345		718,532		718,890	649,925
Diluted EPS (in dollars per share)	$ 1.88		$ 0.68		$ 1.91	$ (1.78)
6.50% Senior Notes | Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate	6.50%				6.50%		6.50%