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Note 16 - Concentration of Risk and Enterprise-wide Disclosures - Contract Revenues by Customer (Details) - Customer Concentration Risk [Member] - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Caltrans [Member] |  |  |  |  |
Contract Revenues | $ 88,627 | $ 96,470 |  | $ 97,637 |
Caltrans [Member] | Sales Revenue, Net [Member] |  |  |  |  |
Concentration Risk Percentage | 12.80% | 15.50% |  | 14.50% |
TxDOT [Member] |  |  |  |  |
Contract Revenues | $ 85,224 | $ 84,129 |  |  |
TxDOT [Member] | Sales Revenue, Net [Member] |  |  |  |  |
Concentration Risk Percentage | 12.40% | 13.50% |  |  |
UDOT [Member] |  |  |  |  |
Contract Revenues | $ 79,421 |  | [1] |  | [1]
UDOT [Member] | Sales Revenue, Net [Member] |  |  |  |  |
Concentration Risk Percentage | 11.50% |  | [1] |  | [1]
[1] | Represents less than 10% of revenues

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611 + Details
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- Definition Costs incurred and are directly related to generating contract revenues. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(e)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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