Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Rent Expense, Net	$ 92	$ 88	$ 80
Leases, Future Minimum Payments Due, Next Twelve Months	73
Leases, Future Minimum Payments, Due in Two Years	61
Leases, Future Minimum Payments, Due in Three Years	47
Leases, Future Minimum Payments, Due in Four Years	39
Leases, Future Minimum Payments, Due in Five Years	31
Leases, Future Minimum Payments, Due Thereafter	111
Leases, Future Minimum Payments Due	362
Purchase Obligations, Future Minimum Payments Due, Current	362
Purchase Obligations, Future Minimum Payments, Due in Two Years	23
Purchase Obligations, Future Minimum Payments, Due in Three Years	12
Purchase Obligations, Future Minimum Payments, Due in Four Years	3
Purchase Obligations, Future Minimum Payments, Due in Five Years	2
Purchase Obligations, Future Minimum Payments, Due Thereafter	7
Purchase Obligations, Future Minimum Payments Due	$ 409