Segment Reporting - Selected Financial Data for Each of Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 3,502	$ 4,238	$ 7,366	$ 8,358
Operating income (loss)	(141)	258	(60)	390
Depreciation and amortization	196	180	379	360
Operating Segments | Transportation
Segment Reporting Information [Line Items]
Revenue	2,127	2,747	4,586	5,406
Operating income (loss)	(15)	243	105	371
Depreciation and amortization	113	108	223	224
Operating Segments | Logistics
Segment Reporting Information [Line Items]
Revenue	1,404	1,526	2,841	3,020
Operating income (loss)	(43)	61	(5)	107
Depreciation and amortization	80	67	149	128
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Operating income (loss)	(83)	(46)	(160)	(88)
Depreciation and amortization	3	5	7	8
Eliminations/Other
Segment Reporting Information [Line Items]
Revenue	(29)	(35)	(61)	(68)
Operating income (loss)	0	0	0	0
Depreciation and amortization	$ 0	$ 0	$ 0	$ 0