Benefit Plans - Components of net cost (benefit) for pension and other postretirement plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Costs and expenses	$ 13	$ (52)
Remeasurement (gains) losses	(53)	(247)
Pension net benefit	(40)	(299)
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	33	29
Interest cost	60	46
Expected return on plan assets	(77)	(110)
Amortization of prior service credit	0	(13)
Costs and expenses	16	(48)
Remeasurement of projected benefit obligation	123	(752)
Remeasurement of plan assets	(180)	529
Remeasurement (gains) losses	(57)	(223)
Pension net benefit	(41)	(271)
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	3	2
Amortization of prior service credit	(6)	(6)
Costs and expenses	(3)	(4)
Remeasurement of projected benefit obligation	4	(24)
Remeasurement of plan assets	0	0
Remeasurement (gains) losses	4	(24)
Pension net benefit	$ 1	$ (28)