Employee Benefit Plans - Postemployment (Details) - Postemployment Retirement Benefits [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Net service cost	$ 4	$ 7	$ 23	$ 26
Defined Benefit Plan, Interest Cost	0	1	2	2
Amortization of prior service cost	(2)	(1)	(4)	(3)
Actuarial loss	0	(1)	0	(3)
Defined Benefit Plan Net Periodic Benefit Costs, Subtotal	$ 2	$ 6	$ 21	$ 22