Employee Benefit Plans - Postretirement Plan (Details) - Postretirement Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 0	$ 0	$ 0	$ 0
Amortization of prior service benefit	0	(1)	(1)	(2)
Net periodic benefit cost (income)	$ 0	$ (1)	$ (1)	$ (2)