Segment Information (Tables)

3 Months Ended

Mar. 31, 2017

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 months ended March 31, 2017 and 2016:

	Three Months Ended March 31,
	2017		2016
United States dollar per Australian dollar	$	0.76	$	0.72
United States dollar per British pound	$	1.24	$	1.43
United States dollar per Canadian dollar	$	0.76	$	0.73
United States dollar per Euro	$	1.07	$	1.10

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 months ended March 31, 2017 and 2016 (dollars in thousands):

	Three Months Ended March 31, 2017
	North American Operations		Australian Operations		U.K./European Operations			Total Operations
Operating revenues:
Freight revenues	$	238,281	$	60,874	$	78,590		$	377,745
Freight-related revenues	65,345		11,709		42,283			119,337
All other revenues	15,850		1,324		4,852			22,026
Total operating revenues	$	319,476	$	73,907	$	125,725		$	519,108
Operating income/(loss)	$	67,570	$	17,159	$	(7,275	)	$	77,454
Depreciation and amortization	$	38,867	$	15,192	$	6,715		$	60,774
Interest expense, net	$	10,551	$	13,987	$	1,600		$	26,138
Provision for/(benefit from) income taxes	$	22,074	$	861	$	(1,007	)	$	21,928
Expenditures for additions to property & equipment, net of grants from outside parties	$	24,215	$	1,462	$	4,290		$	29,967

	Three Months Ended March 31, 2016
	North American Operations		Australian Operations			U.K./European Operations			Total Operations
Operating revenues:
Freight revenues	$	221,825	$	24,777		$	79,812		$	326,414
Freight-related revenues	61,525		25,490			46,443			133,458
All other revenues	16,428		1,531			4,785			22,744
Total operating revenues	$	299,778	$	51,798		$	131,040		$	482,616
Operating income/(loss)	$	69,978	$	(11,751	)	$	(1,231	)	$	56,996
Depreciation and amortization	$	36,189	$	6,656		$	6,485		$	49,330
Interest expense, net	$	10,465	$	2,395		$	5,040		$	17,900
Provision for/(benefit from) income taxes	$	16,009	$	(2,525	)	$	(676	)	$	12,808
Expenditures for additions to property & equipment, net of grants from outside parties	$	25,416	$	867		$	5,400		$	31,683

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 March 31, 2017 and December 31, 2016 (dollars in thousands):

	March 31, 2017
	North American Operations		Australian Operations		U.K./European Operations		Total Operations
Property and equipment, net	$	3,586,131	$	662,839	$	282,449	$	4,531,419

	December 31, 2016
	North American Operations		Australian Operations		U.K./European Operations		Total Operations
Property and equipment, net	$	3,590,625	$	634,148	$	278,546	$	4,503,319