Intangible Assets - Schedule of Identifiable Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Definite-lived intangibles
Gross Carrying Amount	$ 1,959	$ 1,995
Accumulated Amortization	706	560
Customer relationships
Definite-lived intangibles
Gross Carrying Amount	1,891	1,924
Accumulated Amortization	640	494
Trade names
Definite-lived intangibles
Gross Carrying Amount	52	54
Accumulated Amortization	52	52
Non-compete agreements
Definite-lived intangibles
Gross Carrying Amount	16	17
Accumulated Amortization	$ 14	$ 14