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, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Basic EPS:
Net income	$ 717	$ (312)	$ 1,338	$ 10	$ 405	$ 1,348
Basic weighted average common shares outstanding (in shares)	656,965		653,602		656,406	652,801
Basic EPS (in dollars per share)	$ 1.09		$ 2.05		$ 0.62	$ 2.06
Diluted EPS:
Net income	$ 717	$ (312)	$ 1,338	$ 10	$ 405	$ 1,348
Interest expense on 6.50% convertible senior notes	9		12		22	23
Net income for purposes of computing diluted EPS	$ 726		$ 1,350		$ 427	$ 1,371
Basic weighted average common shares outstanding (in shares)	656,965		653,602		656,406	652,801
Dilutive effect of stock awards (in shares)	723		1,307		865	1,185
Dilutive effect of certain PSP Warrants and Treasury Loan Warrants (in shares)	886		2,708		1,713	3,176
Assumed conversion of 6.50% convertible senior notes (in shares)	61,728		61,728		61,728	61,728
Diluted weighted average common shares outstanding (in shares)	720,302		719,345		720,712	718,890
Diluted EPS (in dollars per share)	$ 1.01		$ 1.88		$ 0.59	$ 1.91
6.50% Senior Notes | Senior Notes
Diluted EPS:
Interest rate	6.50%				6.50%