Goodwill and Intangible Assets, Net - Intangible Assets by Major Class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,920	$ 2,918
Accumulated Amortization	2,269	2,027
Net Amount	651	891
Amortization of Intangible Assets	242	243	$ 280
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019	241
2020	238
2021	134
2022	12
2023	$ 6
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Useful Life	11 years
Gross Carrying Amount	$ 2,914	2,907
Accumulated Amortization	2,264	2,022
Net Amount	$ 650	885
Technology, patents and non-compete [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Useful Life	4 years
Gross Carrying Amount	$ 6	11
Accumulated Amortization	5	5
Net Amount	1	$ 6
Commercial Industries segment [Member]
Finite-Lived Intangible Assets [Line Items]
Net Amount	417
Government services [Member]
Finite-Lived Intangible Assets [Line Items]
Net Amount	160
Transportation Services [Member]
Finite-Lived Intangible Assets [Line Items]
Net Amount	$ 74