(Loss) Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares of common stock excluded from the computation of diluted earnings per share (in shares)	22,500	13,800	3,200
(Loss) income (numerator)
Net (loss) income	$ (10,298)	$ (1,548)	$ 2,033
Net (loss) income applicable to common stock for computing basic (loss) earnings per common share	(10,298)	(1,548)	2,033
Net (loss) income as adjusted for purposes of computing diluted (loss) earnings per common share	$ (10,298)	$ (1,548)	$ 2,033
Weighted average number of shares:
Outstanding during period (in shares)	1,006,787	1,028,069	1,077,393
Non-vested restricted stock (in shares)	(23,706)	(20,552)	(17,852)
Weighted average shares outstanding for computing basic (loss) earnings per common share (in shares)	983,081	1,007,517	1,059,541
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)	0	0	10
Shares issuable under incentive compensation plans (in shares)	0	0	7,227
Number of shares as adjusted for purposes of computing diluted (loss) earnings per common share (in shares)	983,081	1,007,517	1,066,778
Basic (loss) earnings per common share (in dollars per share)	$ (10.48)	$ (1.54)	$ 1.92
Diluted (loss) earnings per common share (in dollars per share)	$ (10.48)	$ (1.54)	$ 1.91
Stock Compensation Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares of common stock excluded from the computation of diluted earnings per share (in shares)	300	3,800