(Loss) Earnings Per Common Share - Schedule of Basic and Diluted (Loss) Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
(Loss) Income (numerator)
Net (loss) income	$ (78)	$ 578	$ (8,303)	$ 1,521
Net (loss) income applicable to common stock for computing basic (loss) earnings per common share	(78)	578	(8,303)	1,521
Net (loss) income as adjusted for purposes of computing diluted (loss) earnings per common share	$ (78)	$ 578	$ (8,303)	$ 1,521
Weighted-average number of shares:
Outstanding during period (in shares)	1,008,523	1,034,786	1,006,140	1,031,687
Non-vested restricted stock (in shares)	(24,973)	(21,662)	(23,287)	(20,189)
Weighted average shares outstanding for computing basic (loss) earnings per common share (in shares)	983,550	1,013,124	982,853	1,011,498
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)	0	10	0	10
Shares issuable under incentive compensation plans (in shares)	0	3,879	0	4,773
Number of shares as adjusted for purposes of computing diluted (loss) earnings per common share (in shares)	983,550	1,017,013	982,853	1,016,281
Basic (loss) earnings per common share (in dollars per share)	$ (0.08)	$ 0.57	$ (8.45)	$ 1.50
Diluted (loss) earnings per common share (in dollars per share)	$ (0.08)	$ 0.57	$ (8.45)	$ 1.50