Pension and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost and Other Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Non-operating expense
Total net periodic benefit cost (benefit)	$ (31)	$ (65)	$ (93)	$ (199)
Postretirement Benefits
Operating expense
Service cost	6	10	18	31
Non-operating expense
Interest cost	21	13	66	39
Expected return on plan assets	(20)	(17)	(58)	(52)
Amortization of transition asset	0	0	0	0
Amortization of prior service benefit	(7)	(8)	(23)	(24)
Amortization of net actuarial loss	2	10	6	30
Settlements, curtailments, special termination benefits and other			0	2
Total non-operating expense (benefit)	(4)	(2)	(9)	(5)
Total net periodic benefit cost (benefit)	2	8	9	26
United States | Qualified and Non-qualified Pension Benefits
Operating expense
Service cost	42	64	128	192
Non-operating expense
Interest cost	166	105	497	313
Expected return on plan assets	(243)	(241)	(731)	(723)
Amortization of transition asset	0	0	0	0
Amortization of prior service benefit	(6)	(6)	(18)	(18)
Amortization of net actuarial loss	73	106	220	318
Settlements, curtailments, special termination benefits and other			0	0
Total non-operating expense (benefit)	(10)	(36)	(32)	(110)
Total net periodic benefit cost (benefit)	32	28	96	82
International | Qualified and Non-qualified Pension Benefits
Operating expense
Service cost	21	32	60	100
Non-operating expense
Interest cost	56	32	165	96
Expected return on plan assets	(76)	(69)	(226)	(211)
Amortization of transition asset	1	0	2	1
Amortization of prior service benefit	0	0	1	0
Amortization of net actuarial loss	2	10	6	30
Settlements, curtailments, special termination benefits and other			0	0
Total non-operating expense (benefit)	(17)	(27)	(52)	(84)
Total net periodic benefit cost (benefit)	$ 4	$ 5	$ 8	$ 16