Segment Information (Tables)

6 Months Ended

Jun. 30, 2016

Segment Reporting [Abstract]

Foreign Currency Disclosure [Text Block]

The following table reflects the average exchange rates used to translate the foreign entities respective local currency results of operations into United States dollars for the three and six months ended June 30, 2016 and 2015:

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
United States dollar per Australian dollar	$	0.75	$	0.78	$	0.73	$	0.78
United States dollar per British pound	$	1.44	$	1.53	$	1.43	$	1.52
United States dollar per Canadian dollar	$	0.78	$	0.81	$	0.75	$	0.81
United States dollar per Euro	$	1.13	$	1.11	$	1.12	$	1.12

Schedule of segment reporting information, by segment [Table Text Block]

The following tables set forth selected financial data for the Company's reportable segments for the three and six months ended June 30, 2016 and 2015 (dollars in thousands):

	Three Months Ended June 30, 2016
	North American Operations		Australian Operations		U.K./European Operations			Total Operations
Operating revenues:
Freight revenues	$	227,082	$	26,394	$	87,306		$	340,782
Freight-related revenues	60,978		27,129		45,581			133,688
All other revenues	16,515		1,760		8,630			26,905
Total operating revenues	$	304,575	$	55,283	$	141,517		$	501,375
Operating income/(loss)	$	79,023	$	9,381	$	(1,210	)	$	87,194
Depreciation and amortization	$	37,124	$	7,233	$	6,567		$	50,924
Interest expense, net	$	9,666	$	2,398	$	5,341		$	17,405
Provision for/(benefit from) income taxes	$	20,953	$	2,247	$	(1,088	)	$	22,112
Expenditures for additions to property & equipment, net of grants from outside parties	$	39,523	$	4,787	$	11,338		$	55,648

	Three Months Ended June 30, 2015
	North American Operations		Australian Operations		U.K./European Operations		Total Operations
Operating revenues:
Freight revenues	$	238,153	$	39,464	$	96,998	$	374,615
Freight-related revenues	55,589		25,173		57,129		137,891
All other revenues	17,238		2,171		10,304		29,713
Total operating revenues	$	310,980	$	66,808	$	164,431	$	542,219
Operating income	$	76,621	$	15,131	$	7,699	$	99,451
Depreciation and amortization	$	34,936	$	7,394	$	5,718	$	48,048
Interest expense, net	$	9,588	$	2,271	$	5,789	$	17,648
Provision for income taxes	$	24,939	$	3,829	$	532	$	29,300
Expenditures for additions to property & equipment, net of grants from outside parties	$	73,440	$	9,159	$	5,028	$	87,627

Property and equipment by segment [Table Text Block]

The following tables set forth the property and equipment recorded in the consolidated balance sheets for the Company's reportable segments as of June 30, 2016 and December 31, 2015 (dollars in thousands):

	June 30, 2016
	North American Operations		Australian Operations		U.K./European Operations		Total Operations
Property and equipment, net	$	3,462,559	$	452,455	$	293,692	$	4,208,706

	December 31, 2015
	North American Operations		Australian Operations		U.K./European Operations		Total Operations
Property and equipment, net	$	3,433,669	$	465,123	$	316,271	$	4,215,063