Defined Benefit Postretirement Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Amortization:
Estimated future contributions over the remainder of the current year	$ 12
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	$ 4
Interest cost	2	2
Expected return on plan assets	(2)	(2)
Amortization:
– prior service credit	(2)	(2)
– actuarial loss	0	2
Net periodic benefit costs (credits)	2	4
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	0	0
Expected return on plan assets	0	0
Amortization:
– prior service credit	(4)	(4)
– actuarial loss	1	1
Net periodic benefit costs (credits)	(3)	$ (3)
Payment for other postretirement benefits	3
Funded Plan
Amortization:
Payment for pension benefits	$ 5