Benefit Plans - Components of net cost (benefit) for pension and other postretirement plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Costs and expenses	$ (10)	$ (54)	$ (97)	$ (164)
Remeasurement (gains) losses	79	40	91	(404)
Pension net cost (benefit)	69	(14)	(6)	(568)
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	22	27	79	78
Interest cost	59	47	157	145
Expected return on plan assets	(85)	(112)	(295)	(338)
Amortization of prior service credit	(2)	(13)	(27)	(38)
Costs and expenses	(6)	(51)	(86)	(153)
Remeasurement of projected benefit obligation	(254)	(25)	(1,427)	(292)
Remeasurement of plan assets	335	68	1,563	(99)
Remeasurement (gains) losses	81	43	136	(391)
Pension net cost (benefit)	75	(8)	50	(544)
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	3	2	7	6
Amortization of prior service credit	(7)	(5)	(19)	(18)
Costs and expenses	(4)	(3)	(11)	(11)
Remeasurement of projected benefit obligation	(2)	(3)	(45)	(13)
Remeasurement of plan assets	0	0	0	0
Remeasurement (gains) losses	(2)	(3)	(45)	(13)
Pension net cost (benefit)	$ (6)	$ (6)	$ (56)	$ (24)