Employee Benefit Plans - Schedule of Amount Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	$ 13	$ 57
Current Liabilities	(16)	(15)
Long-term Liabilities	(324)	(211)
Net Amount Recognized in Consolidated Balance Sheets	(327)	(169)
Post-retirement Benefits
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	0	0
Current Liabilities	(34)	(38)
Long-term Liabilities	(84)	(212)
Net Amount Recognized in Consolidated Balance Sheets	$ (118)	$ (250)