Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3	$ 5	$ 5
Interest cost	1	2	3	4
Expected return on assets	(2)	(3)	(4)	(5)
Prior service credit	0	0	0	0
Net periodic benefit cost (credit)	2	2	4	4
Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	0	1	1	2
Expected return on assets	0	0	0	0
Prior service credit	(3)	(4)	(6)	(7)
Net periodic benefit cost (credit)	$ (3)	$ (2)	$ (5)	$ (4)