Earnings 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, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Basic EPS:
Net income	$ 599	$ (473)	$ 717	$ (312)	$ 126	$ 405
Weighted average common shares outstanding (in thousands), basic (in shares)	660,127		656,965		659,504	656,406
Basic EPS (in dollars per share)	$ 0.91		$ 1.09		$ 0.19	$ 0.62
Diluted EPS:
Net income	$ 599	$ (473)	$ 717	$ (312)	$ 126	$ 405
Interest expense on 6.50% convertible senior notes	0		9		0	22
Net income for purposes of computing diluted EPS	$ 599		$ 726		$ 126	$ 427
Basic weighted average common shares outstanding (in shares)	660,127		656,965		659,504	656,406
Dilutive effect of restricted stock unit awards (in shares)	240		723		370	865
Dilutive effect of certain PSP Warrants and Treasury Loan Warrants (in shares)	0		886		649	1,713
Assumed conversion of 6.50% convertible senior notes (in shares)	0		61,728		0	61,728
Diluted weighted average common shares outstanding (in shares)	660,367		720,302		660,523	720,712
Diluted EPS (in dollars per share)	$ 0.91		$ 1.01		$ 0.19	$ 0.59
6.50% Senior Notes | Senior Notes
Diluted EPS:
Interest rate	6.50%				6.50%