Employee Benefit Plans - Schedule Fair Value of the Pension Assets (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	$ 1,866	$ 2,059	$ 567
U.S. equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	215	207
Global equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	338	551
Fixed income and cash investment funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	937	658
U.S. corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	0	70
Other debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	4	55
Private equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	60	107
Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	35	44
Other investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair values of the plan assets by asset category and by levels of fair value	$ 277	$ 367