Employee Benefit Plans - Schedule of Pre-tax Change in Other Comprehensive Loss (Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Recognized in the Balance Sheet
Losses (Gains)	$ 21	$ 223
Expense (Income) Recognized in the Income Statement
Amortization of Net Loss	30	41	$ 41
Settlement (Gain) Loss	0	(1)	11
Amortization of Prior Service Costs	0	0	0
Amortization of net losses estimated to be expensed in next fiscal year	57
Post-retirement Benefits
Recognized in the Balance Sheet
Losses (Gains)	22	(112)
Expense (Income) Recognized in the Income Statement
Amortization of Net Loss	0	0	0
Settlement (Gain) Loss	0	0	0
Amortization of Prior Service Costs	$ (7)	$ (2)	$ 0