Special Charges (Credits) - Components of Special Charges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Other Income and Expenses [Abstract]
CARES Act grant	$ 0	$ (1,132)	$ 0	$ (4,021)
Severance and benefit costs	0	5	0	433
Impairment of assets	0	46	0	105
(Gains) losses on sale of assets and other special charges	20	(17)	124	60
Total operating special charges (credits)	20	(1,098)	124	(3,423)
Nonoperating unrealized (gains) losses on investments, net	(28)	34	12	(91)
Nonoperating debt extinguishment and modification fees	0	(12)	7	50
Nonoperating special termination benefits	0	0	0	46
Total nonoperating special charges and unrealized (gains) losses on investments, net	(28)	22	19	5
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net	(8)	(1,076)	143	(3,418)
Income tax (benefit) expense, net of valuation allowance	(7)	274	(17)	768
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes	$ (15)	$ (802)	$ 126	$ (2,650)