Employee Benefit Plans - Schedule of Amount Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	$ 29	$ 25
Current Liabilities	(16)	(17)
Long-term Liabilities	(270)	(305)
Net Amount Recognized in Consolidated Balance Sheets	(257)	(297)
Post-retirement Benefits
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	0	0
Current Liabilities	(17)	(20)
Long-term Liabilities	(79)	(97)
Net Amount Recognized in Consolidated Balance Sheets	$ (96)	$ (117)