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U.K. Operations Optimization Restructuring Reserve Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs	$ 3,286	$ 2,628	$ 12,931	$ 8,744
U.K. Operations Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related liability, beginning balance			0
Restructuring and related costs	3,491		12,846
Cash payments			(5,769)
Non-cash settlements			(1,120)
Restructuring and related liability, ending balance	5,957		5,957
U.K. Operations Optimization [Member] \| Rationalization of locomotive and railcar fleet [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related liability, beginning balance			0
Restructuring and related costs	379		6,317
Cash payments			(797)
Non-cash settlements			(897)
Restructuring and related liability, ending balance	4,623		4,623
U.K. Operations Optimization [Member] \| Management restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related liability, beginning balance			0
Restructuring and related costs	1,610		3,739
Cash payments			(2,405)
Non-cash settlements			0
Restructuring and related liability, ending balance	1,334		1,334
U.K. Operations Optimization [Member] \| Productivity and automation investments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related liability, beginning balance			0
Restructuring and related costs	1,502		2,790
Cash payments			(2,567)
Non-cash settlements			(223)
Restructuring and related liability, ending balance	$ 0		$ 0