Revenue Recognition - Disaggregation of Revenue by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 4,221	$ 4,154	$ 11,587	$ 12,512
United States
Disaggregation of Revenue [Line Items]
Revenue	2,441	2,460	6,674	7,335
North America (excluding United States)
Disaggregation of Revenue [Line Items]
Revenue	89	93	255	266
France
Disaggregation of Revenue [Line Items]
Revenue	488	484	1,340	1,529
United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	565	509	1,512	1,532
Europe (excluding France and United Kingdom)
Disaggregation of Revenue [Line Items]
Revenue	610	581	1,706	1,770
Other
Disaggregation of Revenue [Line Items]
Revenue	28	27	100	80
Eliminations/Other
Disaggregation of Revenue [Line Items]
Revenue	(34)	(40)	(95)	(108)
Eliminations/Other | United States
Disaggregation of Revenue [Line Items]
Revenue	(14)	(12)	(33)	(24)
Eliminations/Other | North America (excluding United States)
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Eliminations/Other | France
Disaggregation of Revenue [Line Items]
Revenue	(3)	(6)	(9)	(17)
Eliminations/Other | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	(12)	(18)	(39)	(54)
Eliminations/Other | Europe (excluding France and United Kingdom)
Disaggregation of Revenue [Line Items]
Revenue	(5)	(3)	(12)	(11)
Eliminations/Other | Other
Disaggregation of Revenue [Line Items]
Revenue	0	(1)	(2)	(2)
Transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	2,675	2,684	7,261	8,090
Transportation | Operating Segments | United States
Disaggregation of Revenue [Line Items]
Revenue	1,904	1,891	5,111	5,651
Transportation | Operating Segments | North America (excluding United States)
Disaggregation of Revenue [Line Items]
Revenue	77	76	219	216
Transportation | Operating Segments | France
Disaggregation of Revenue [Line Items]
Revenue	317	326	883	1,041
Transportation | Operating Segments | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	175	192	482	566
Transportation | Operating Segments | Europe (excluding France and United Kingdom)
Disaggregation of Revenue [Line Items]
Revenue	194	195	528	603
Transportation | Operating Segments | Other
Disaggregation of Revenue [Line Items]
Revenue	8	4	38	13
Transportation | Eliminations/Other
Disaggregation of Revenue [Line Items]
Revenue	(43)	(53)	(125)	(130)
Logistics | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	1,580	1,510	4,421	4,530
Logistics | Operating Segments | United States
Disaggregation of Revenue [Line Items]
Revenue	551	581	1,596	1,708
Logistics | Operating Segments | North America (excluding United States)
Disaggregation of Revenue [Line Items]
Revenue	12	17	36	50
Logistics | Operating Segments | France
Disaggregation of Revenue [Line Items]
Revenue	174	164	466	505
Logistics | Operating Segments | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	402	335	1,069	1,020
Logistics | Operating Segments | Europe (excluding France and United Kingdom)
Disaggregation of Revenue [Line Items]
Revenue	421	389	1,190	1,178
Logistics | Operating Segments | Other
Disaggregation of Revenue [Line Items]
Revenue	$ 20	$ 24	$ 64	$ 69