Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets
Accumulated amortization	$ 142	$ 102
Net Carrying Amount	400	439
Amortization expense	40	$ 41	$ 39
Impairment of intangible assets	$ 0
Customer list intangibles
Finite-Lived Intangible Assets
Useful life	20 years
2019	$ 42
2020	41
2021	39
2022	36
2023	$ 32