Special Charges (Credits) - Components of Special Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Other Income and Expenses [Abstract]
CARES Act grant	$ 0	$ (1,079)	$ 0	$ (2,889)
Severance and benefit costs	0	11	0	428
Impairment of assets	0	59	0	59
(Gains) losses on sale of assets and other special charges	112	61	104	77
Total operating special charges (credits)	112	(948)	104	(2,325)
Nonoperating unrealized (gains) losses on investments, net	40	(147)	40	(125)
Nonoperating debt extinguishment and modification fees	0	62	7	62
Nonoperating special termination benefits	0	0	0	46
Total nonoperating special charges and unrealized (gains) losses on investments, net	40	(85)	47	(17)
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net	152	(1,033)	151	(2,342)
Income tax (benefit) expense, net of valuation allowance	(10)	203	(10)	494
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes	$ 142	$ (830)	$ 141	$ (1,848)