Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
ROU asset	$ 126	$ 126	$ 0
Operating lease liability	137	137	$ 0
Short-term lease cost (less than $1)	0	1
Finance lease liability	$ 3	$ 3
Minimum
Lessee, Lease, Description [Line Items]
Term of lease	1 year	1 year
Term of extension	3 years	3 years
Maximum
Lessee, Lease, Description [Line Items]
Term of lease	10 years	10 years
Term of extension	5 years	5 years