Benefit Plans - Components of net cost (benefit) for pension and other postretirement plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Costs and expenses	$ (35)	$ (48)	$ (87)	$ (110)
Remeasurement (gains) losses	259	(134)	12	(444)
Pension net cost (benefit)	224	(182)	(75)	(554)
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	28	25	57	51
Interest cost	52	52	98	98
Expected return on plan assets	(100)	(109)	(210)	(226)
Amortization of prior service credit	(12)	(12)	(25)	(25)
Costs and expenses	(32)	(44)	(80)	(102)
Remeasurement of projected benefit obligation	(421)	245	(1,173)	(267)
Remeasurement of plan assets	699	(388)	1,228	(167)
Remeasurement (gains) losses	278	(143)	55	(434)
Pension net cost (benefit)	246	(187)	(25)	(536)
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	1
Interest cost	2	2	4	4
Amortization of prior service credit	(6)	(7)	(12)	(13)
Costs and expenses	(3)	(4)	(7)	(8)
Remeasurement of projected benefit obligation	(19)	9	(43)	(10)
Remeasurement of plan assets	0	0	0	0
Remeasurement (gains) losses	(19)	9	(43)	(10)
Pension net cost (benefit)	$ (22)	$ 5	$ (50)	$ (18)