Segment Reporting (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Share-based compensation expense	$ 18,664	$ 21,181	$ 20,905
Depreciation expense	1,187,050	1,121,966	1,047,049
Used vehicle sales, net	(972)	(99,853)	(116,060)
Pension lump sum settlement expense	0	0	97,231
Amortization expense and other non-cash charges, net	68,260	70,762	47,263
Interest expense	147,843	150,434	144,739
Capital expenditures paid	1,905,157	2,667,978	2,259,164
Total assets	10,902,454	10,952,580	9,837,776
Operating Segments | Fleet Management Solutions
Segment Reporting Information [Line Items]
Share-based compensation expense	5,464	5,672	4,895
Depreciation expense	1,156,888	1,092,750	1,018,017
Used vehicle sales, net	(724)	(99,758)	(115,646)
Pension lump sum settlement expense			76,239
Amortization expense and other non-cash charges, net	34,652	36,348	19,936
Interest expense	151,297	154,276	147,247
Capital expenditures paid	1,814,146	2,595,961	2,166,319
Total assets	9,954,452	10,061,092	8,998,788
Operating Segments | Dedicated Transportation Solutions
Segment Reporting Information [Line Items]
Share-based compensation expense	1,254	1,155	720
Depreciation expense	3,222	3,184	3,211
Used vehicle sales, net	(90)	(54)	5
Pension lump sum settlement expense			3,335
Amortization expense and other non-cash charges, net	1,027	1,878	516
Interest expense	(1,901)	(1,597)	(1,520)
Capital expenditures paid	2,551	3,570	1,883
Total assets	255,845	275,634	211,388
Operating Segments | Supply Chain Solutions
Segment Reporting Information [Line Items]
Share-based compensation expense	2,764	3,400	3,661
Depreciation expense	25,956	25,721	25,636
Used vehicle sales, net	(158)	(41)	(419)
Pension lump sum settlement expense			3,277
Amortization expense and other non-cash charges, net	3,215	2,971	1,309
Interest expense	(1,663)	(2,174)	(807)
Capital expenditures paid	64,186	27,841	20,941
Total assets	713,190	636,647	673,876
Central Support Service
Segment Reporting Information [Line Items]
Share-based compensation expense	9,182	10,954	11,629
Depreciation expense	984	311	185
Used vehicle sales, net	0	0	0
Pension lump sum settlement expense			14,380
Amortization expense and other non-cash charges, net	29,366	29,565	25,502
Interest expense	110	(71)	(181)
Capital expenditures paid	24,274	40,606	70,021
Total assets	198,394	202,129	193,484
Eliminations
Segment Reporting Information [Line Items]
Share-based compensation expense	0	0	0
Depreciation expense	0	0	0
Used vehicle sales, net	0	0	0
Pension lump sum settlement expense			0
Amortization expense and other non-cash charges, net	0	0	0
Interest expense	0	0	0
Capital expenditures paid	0	0	0
Total assets	$ (219,427)	$ (222,922)	$ (239,760)