Lease Arrangements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Lease Arrangements Textuals [Abstract]
Operating Leases, Longest Term, Year	2029
Operating leases, rent expense, net	$ 26	$ 24	$ 22
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	27
Operating Leases, Future Minimum Payments, Due in Two Years	29
Operating Leases, Future Minimum Payments, Due in Three Years	23
Operating Leases, Future Minimum Payments, Due in Four Years	21
Operating Leases, Future Minimum Payments, Due in Five Years	12
Operating Leases, Future Minimum Payments, Due Thereafter	45
Operating Leases, Future Minimum Payments Due	157
Sublease proceeds	(2)
Net lease commitments	$ 155