Employee Benefit Plans - Schedule of Components of Net Periodic Cost (Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 21	$ 21	$ 37
Interest cost	90	71	51
Expected return on plan assets	(122)	(121)	(81)
Amortization of prior service credit	1	0	0
Amortization of net actuarial loss (gain)	17	10	12
Curtailment / settlement loss (gain)	9	2	(45)
Net periodic cost (income)	16	(17)	(26)
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1	2	2
Interest cost	4	5	6
Expected return on plan assets	0	0	0
Amortization of prior service credit	(3)	(5)	(3)
Amortization of net actuarial loss (gain)	(7)	(2)	(2)
Curtailment / settlement loss (gain)	0	(5)	2
Net periodic cost (income)	$ (5)	$ (5)	$ 5