Pension and Other Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	1	2	4	5
Less Expected return on plan assets	(2)	(2)	(6)	(6)
Amortization of net actuarial loss (gain)	0	1	1	2
Amortization of prior service cost	0	0	0	0
Settlement expense (income)	0	4	0	4
Net periodic benefit cost	(1)	5	(1)	5
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	0	0	0
Less Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss (gain)	0	0	(1)	0
Amortization of prior service cost	0	0	0	0
Settlement expense (income)	0	0	0	0
Net periodic benefit cost	0	0	(1)	0
Supplemental Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	0	0	0
Less Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss (gain)	0	0	0	0
Amortization of prior service cost	0	0	0	0
Settlement expense (income)	0	0	0	0
Net periodic benefit cost	$ 0	$ 0	$ 0	$ 0