Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
PRB plans	$ 5	$ 0
Defined contribution plans	311	271
Liability, Defined Benefit Plan, Current	310		$ 310
Liability, Defined Benefit Pension Plan, Noncurrent	7,709		7,855
Non-service pension income	(480)	(491)
Total net periodic benefit (income) expense	(360)	(358)
Marketable securities held in trusts	857		965
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	12	7
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	3,538		3,214
Liability, Defined Benefit Pension Plan, Noncurrent	6,748		6,873
Service cost	118	131
Interest cost	382	312
Expected return on plan assets	(890)	(868)
Amortization of prior service credit	(42)	(42)
Recognized actuarial net loss (gain)	77	109
Net settlement, curtailment and special termination benefit gain	(6)	0
Non-service pension income	(479)	(489)
Total net periodic benefit (income) expense	(361)	(358)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Pension Plan, Noncurrent	898		903
Service cost	2	2
Interest cost	7	6
Expected return on plan assets	(5)	(5)
Amortization of prior service credit	0	(1)
Recognized actuarial net loss (gain)	(3)	(2)
Net settlement, curtailment and special termination benefit gain	0	0
Non-service pension income	(1)	(2)
Total net periodic benefit (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	$ 63		$ 79