Segment Information Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) reportable_segment provinces region	Jun. 30, 2016 USD ($)	Dec. 01, 2016
Segment Reporting Information [Line Items]
Number of operating regions | region			10
Number of reportable segments | reportable_segment			3
Noncontrolling Interest, Ownership Percentage by Parent					51.10%
Freight revenues	$ 383,155	$ 340,782	$ 760,900	$ 667,196
Freight-related revenues	127,621	133,688	246,958	267,146
All other revenues	29,657	26,905	51,683	49,649
Total Operating revenues	540,433	501,375	1,059,541	983,991
Operating Income (Loss)	101,340	87,194	178,794	144,190
Depreciation and amortization	61,513	50,924	122,287	100,254
Interest expense, net	(25,204)	17,405	(51,342)	(35,305)
Provision for/(benefit from) income taxes	29,597	22,112	51,525	34,920
Expenditures for Additions to Property and Equipment Net of Grants From Outside Parties	46,916	55,648	$ 79,868	87,331
North American Operations [Member]
Segment Reporting Information [Line Items]
Number of operating regions | provinces			8
Freight revenues	238,373	227,082	$ 476,654	448,907
Freight-related revenues	61,183	60,978	126,528	122,503
All other revenues	16,118	16,515	31,968	32,943
Total Operating revenues	315,674	304,575	635,150	604,353
Operating Income (Loss)	79,586	79,023	147,156	149,001
Depreciation and amortization	38,919	37,124	77,786	73,313
Interest expense, net	9,560	9,666	20,111	20,130
Provision for/(benefit from) income taxes	27,789	20,953	49,863	36,962
Expenditures for Additions to Property and Equipment Net of Grants From Outside Parties	40,012	39,523	64,227	64,939
Australian Operations [Member]
Segment Reporting Information [Line Items]
Freight revenues	63,753	26,394	124,627	51,171
Freight-related revenues	11,500	27,129	23,209	52,619
All other revenues	1,556	1,760	2,880	3,291
Total Operating revenues	76,809	55,283	150,716	107,081
Operating Income (Loss)	20,250	9,381	37,409	(2,370)
Depreciation and amortization	14,970	7,233	30,162	13,889
Interest expense, net	13,835	2,398	27,822	4,793
Provision for/(benefit from) income taxes	1,931	2,247	2,792	(277)
Expenditures for Additions to Property and Equipment Net of Grants From Outside Parties	3,714	4,787	5,176	5,654
U.K./European Operations [Member]
Segment Reporting Information [Line Items]
Freight revenues	81,029	87,306	159,619	167,118
Freight-related revenues	54,938	45,581	97,221	92,024
All other revenues	11,983	8,630	16,835	13,415
Total Operating revenues	147,950	141,517	273,675	272,557
Operating Income (Loss)	1,504	(1,210)	(5,771)	(2,441)
Depreciation and amortization	7,624	6,567	14,339	13,052
Interest expense, net	1,809	5,341	3,409	10,382
Provision for/(benefit from) income taxes	(123)	(1,088)	(1,130)	(1,765)
Expenditures for Additions to Property and Equipment Net of Grants From Outside Parties	$ 3,190	$ 11,338	$ 10,465	$ 16,738
MIRA [Member]
Segment Reporting Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners					48.90%