Pension and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost and Other Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Non-operating expense
Total net periodic benefit cost (benefit)	$ (67)	$ (80)	$ (134)	$ (159)
Postretirement Benefits
Operating expense
Service cost	10	11	21	23
Non-operating expense
Interest cost	13	11	26	22
Expected return on plan assets	(17)	(20)	(35)	(39)
Amortization of transition asset	0	0	0	0
Amortization of prior service benefit	(9)	(8)	(16)	(16)
Amortization of net actuarial loss	10	14	20	28
Settlements, curtailments, special termination benefits and other	1	1	2	2
Total non-operating expense (benefit)	(2)	(2)	(3)	(3)
Total net periodic benefit cost (benefit)	8	9	18	20
UNITED STATES | Qualified and Non-qualified Pension Benefits
Operating expense
Service cost	64	72	128	144
Non-operating expense
Interest cost	104	90	208	180
Expected return on plan assets	(241)	(264)	(482)	(528)
Amortization of transition asset	0	0	0	0
Amortization of prior service benefit	(6)	(6)	(12)	(12)
Amortization of net actuarial loss	106	132	212	264
Settlements, curtailments, special termination benefits and other	0	0	0	0
Total non-operating expense (benefit)	(37)	(48)	(74)	(96)
Total net periodic benefit cost (benefit)	27	24	54	48
International | Qualified and Non-qualified Pension Benefits
Operating expense
Service cost	33	42	68	84
Non-operating expense
Interest cost	32	25	64	50
Expected return on plan assets	(70)	(82)	(142)	(163)
Amortization of transition asset	1	1	1	1
Amortization of prior service benefit	0	(1)	0	(2)
Amortization of net actuarial loss	9	27	20	54
Settlements, curtailments, special termination benefits and other	0	0	0	0
Total non-operating expense (benefit)	(28)	(30)	(57)	(60)
Total net periodic benefit cost (benefit)	$ 5	$ 12	$ 11	$ 24