Changes in Operations Europe - Freightliner (Details) £ in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($) $ / £	Mar. 31, 2015 GBP (£)	Mar. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($) $ / £	Mar. 25, 2015 GBP (£) rail_car employee locomotive $ / £	Mar. 25, 2015 USD ($) rail_car employee locomotive $ / £
Foreign currency exchange rate | $ / £		1.51				1.51	1.49	1.49
Operating revenues	$ 501,375	$ 542,219			$ 983,991	$ 939,249
Operating income	87,194	99,451			144,190	172,071
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 0	0			$ 0	18,686
Freightliner [Member]
Business Acquisition, Effective Date of Acquisition			Mar. 25, 2015	Mar. 25, 2015
Business Acquisition, Name of Acquired Entity			Freightliner Group Limited (Freightliner)	Freightliner Group Limited (Freightliner)
Percentage of economic interest retained by acquiree's management			6.00%	6.00%
Number of employees | employee							2,500	2,500
Leased locomotives | locomotive							250	250
Electric locomotives | locomotive							45	45
Railcars | rail_car							5,500	5,500
Cash consideration			£ 492,083	$ 733,006
Deferred consideration			24,200	36,048
Total consideration			£ 516,283	$ 769,054
Contingent liability							£ 24,200	$ 36,000
Operating revenues						186,200
Operating income						8,900
Acquisition-related costs		$ 700				$ 13,300