Commitments and Contingent Liabilites (Narrative) (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017 USD ($) tie	Dec. 31, 2014 USD ($) tie	Dec. 31, 2013 tie	Dec. 31, 2012 USD ($)	Dec. 31, 2016 USD ($)
Product Liability Contingency [Line Items]
Accrued warranty	$ 9,168				$ 10,154
Concrete ties manufactured | tie	3,000,000
Warranty period				10 years
Accrual for environmental loss	$ 6,253				6,270
Reserve for Concrete Ties
Product Liability Contingency [Line Items]
Accrued warranty	$ 7,584				$ 7,574
Warranty period				5 years
2005 Contract
Product Liability Contingency [Line Items]
Concrete ties manufactured ratio | tie	1.5
Period in which concrete ties will be replaced after sale	5 years
Warranty Policy
Product Liability Contingency [Line Items]
Warranty period				15 years
Warranty Ratio				1
The UPRR
Product Liability Contingency [Line Items]
Concrete ties manufactured | tie	1,600,000
Warranty period				5 years
Warranty Ratio				1.5
The UPRR | Reserve for Concrete Ties
Product Liability Contingency [Line Items]
Litigation settlement amount				$ 12,000
Product warranty expense				$ 22,000
Cure period to claim		90 days
Change in standard product warranty accrual		$ 8,766
Unreconciled warranty ties | tie		90,100
The UPRR | Warranty Policy
Product Liability Contingency [Line Items]
Ties manufactured that did not meet criteria to be covered as warranty replacement ties | tie			170,000