XML 44 R75.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Financial instruments and risk management - Risk management (Details) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Concentration Risk [Line Items] |  |
General payment terms | 30 days |
Customer A | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 29.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerMember | 0.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerMember
Customer A | Accounts receivable and unbilled revenue | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 49.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerMember | 0.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerMember
Customer B | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 28.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerBMember | 29.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerBMember
Customer B | Accounts receivable and unbilled revenue | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 26.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerBMember | 28.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerBMember
Customer C | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 14.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerCMember | 22.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerCMember
Customer C | Accounts receivable and unbilled revenue | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 11.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerCMember | 17.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerCMember
Customer D | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 11.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerDMember | 8.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerDMember
Customer D | Accounts receivable and unbilled revenue | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 0.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerDMember | 26.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = noa_AccountsReceivableAndUnbilledRevenueMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerDMember
Customer E | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 6.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerEMember | 10.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerEMember
Customer F | Total revenues | Major customers |  |
Concentration Risk [Line Items] |  |
Concentration risk, percentage | 1.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerFMember | 18.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueProductLineMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = noa_CustomerFMember

X
- Definition Accounts Receivable, General Payment Terms + References No definition available. + Details
Name: | noa_AccountsReceivableGeneralPaymentTerms
Namespace Prefix: | noa_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ConcentrationRiskLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611 Reference 2: 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=6927468&loc=d3e6404-108592 Reference 3: 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=28364263&loc=d3e13531-108611 Reference 4: 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=6927468&loc=d3e6351-108592 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerDMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerEMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerFMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorCustomersAxis=noa_CustomerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |