Employment Benefit Plans Postretirement Health Care and Other Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Postemployment Benefits, Period Expense	$ 3	$ 1	$ 5
Unfunded Accumulated Postretirement Benefit Obligations Determined By Company	$ 8
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.00%	4.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 0
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	1
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	3
Defined Benefit Plan, Benefit Obligation	$ 5
Maximum [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	5.30%
Minimum [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	4.50%