Employee Benefit Plans - Schedule of Reconciliation to Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	$ 395	$ 177
Net prior service cost (credit)	19	20
Total	414	197
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	(38)	(29)
Net prior service cost (credit)	(15)	(18)
Total	$ (53)	$ (47)