Contingencies and Commitments Commitments - Operating Leases Table (Details) $ in Millions	Dec. 31, 2017 USD ($)
Other Commitments [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 6
Operating Leases, Future Minimum Payments, Due in Two Years	5
Operating Leases, Future Minimum Payments, Due in Three Years	2
Operating Leases, Future Minimum Payments, Due in Four Years	1
Operating Leases, Future Minimum Payments Due	$ 14