Employee Benefit Plans - Postretirement Plan (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 0	$ 0	$ 0	$ 0
Amortization of prior service benefit	(1)	(2)	(2)	(4)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(1)	(1)	(1)	(1)
Net periodic benefit cost (income)	0	(1)	(1)	(3)
Plan assets contributions by employer	0		1
Postemployment Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0	0	1	2
Amortization of prior service benefit	0	0	(1)	(2)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	1	$ 1	3	$ 2
Plan assets contributions by employer	$ 4		$ 11