Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income (numerator)
Net income	$ 57	$ 511
Net income applicable to common stock for computing basic earnings per common share	57	511
Net income as adjusted for purposes of computing diluted earnings per common share	$ 57	$ 511
Weighted-average number of shares:
Outstanding during period (in shares)	1,011,350	1,003,666
Non-vested restricted stock (in shares)	(26,495)	(22,111)
Weighted average shares outstanding for computing basic earnings per common share (in shares)	984,855	981,555
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)	10	10
Shares issuable under incentive compensation plans (in shares)	1,397	718
Number of shares as adjusted for purposes of computing diluted earnings per common share (in shares)	986,262	982,283
Basic earnings per common share (in dollars per share)	$ 0.06	$ 0.52
Diluted earnings per common share (in dollars per share)	$ 0.06	$ 0.52
Number of shares of common stock excluded from the computation of diluted earnings per share (in shares)	20,200	21,200