Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
PRB plans	$ 9	$ 4
Defined contribution plans	395	372
Liability, Defined Benefit Plan, Current	270		$ 270
Liability, Defined Benefit Pension Plan, Noncurrent	2,320		2,385
Non-service pension income	(386)	(444)
Marketable securities held in trusts	705		745
UNITED STATES
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plans	0	0
Foreign Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plans	2	8
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	1,600		1,296
Liability, Defined Benefit Pension Plan, Noncurrent	1,679		1,737
Service cost	47	55
Interest cost	596	626
Expected return on plan assets	(937)	(937)
Amortization of prior service credit	(43)	(39)
Recognized actuarial net (gain) loss	5	(95)
Net settlement, curtailment, and special termination benefit (gain) loss	(7)	2
Non-service pension income	(386)	(443)
Total net periodic (income) expense	(339)	(388)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Pension Plan, Noncurrent	580		582
Service cost	1	1
Interest cost	11	12
Expected return on plan assets	(5)	(5)
Amortization of prior service credit	0	0
Recognized actuarial net (gain) loss	(6)	(8)
Net settlement, curtailment, and special termination benefit (gain) loss	0	0
Non-service pension income	0	(1)
Total net periodic (income) expense	1	$ 0
Other pension and PRB related items
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Pension Plan, Noncurrent	$ 61		$ 66