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Commitments and Contingent Liabilites (Narrative) (Details) $ in Thousands, item in Millions | 12 Months Ended | 168 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 USD ($) | Dec. 31, 2012 USD ($) | Dec. 31, 2011 item | Mar. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Product Liability Contingency [Line Items] |  |  |  |  |
Concrete Ties Manufactured | item |  |  | 3.0 |  |
Standard Product Warranty Accrual |  |  |  | $ 8,731 | $ 8,755
Accrual for Environmental Loss Contingencies |  |  |  | 6,612 | 6,640
Reserve for Concrete Ties [Member] |  |  |  |  |
Product Liability Contingency [Line Items] |  |  |  |  |
Litigation Settlement, Amount |  | $ 12,000 |  |  |
Product Warranty Expense |  | $ 22,000 |  |  |
Standard Product Warranty Accrual |  |  |  | $ 7,461 | $ 7,544
Standard Product Warranty Accrual, Period Increase (Decrease) | $ 8,766 |  |  |  |
The UPRR [Member] |  |  |  |  |
Product Liability Contingency [Line Items] |  |  |  |  |
Concrete Ties Manufactured | item |  |  | 1.6 |  |

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 + Details
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