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v2.4.1.9

Shares - Common stock issued and outstanding (Details) (CAD) In Thousands, except Share data, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance, issued (shares) | 34,746,236 us-gaap_CommonStockSharesIssued |  | 36,251,006 us-gaap_CommonStockSharesIssued |
Beginning balance, outstanding (shares) | 34,746,236 us-gaap_CommonStockSharesOutstanding |  | 36,251,006 us-gaap_CommonStockSharesOutstanding |
Issued upon exercise of stock options (shares) |  |  | 295,230 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |
Purchase of treasury shares for settlement of certain equity classified stock-based compensation | (589,892)us-gaap_TreasuryStockSharesAcquired |  |  |
Retired through Share Purchase Program (shares) | (500,000)noa_StockRepurchaseProgramNumberofSharestobePurchasedandRetired |  | (1,800,000)noa_StockRepurchaseProgramNumberofSharestobePurchasedandRetired |
Ending balance, issued (shares) | 34,923,916 us-gaap_CommonStockSharesIssued |  | 34,746,236 us-gaap_CommonStockSharesIssued |
Ending balance, outstanding (shares) | 34,334,024 us-gaap_CommonStockSharesOutstanding |  | 34,746,236 us-gaap_CommonStockSharesOutstanding |
Earnings Per Share [Abstract] |  |  |  |
Net loss from continuing operations | (697)us-gaap_IncomeLossFromContinuingOperations |  | (18,047)us-gaap_IncomeLossFromContinuingOperations |
Net (loss) income from discontinued operations | (472)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity |  | 87,231 us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity |
Net (loss) income | (1,169)us-gaap_NetIncomeLoss |  | 69,184 us-gaap_NetIncomeLoss |
Weighted average number of shares outstanding, basic |  |  |  |
Weighted average number of common shares (in shares) | 35,014,418 us-gaap_WeightedAverageNumberOfSharesOutstandingBasic |  | 36,269,996 us-gaap_WeightedAverageNumberOfSharesOutstandingBasic |
Basic per share information |  |  |  |
Net loss from continuing operations (in CAD per share) | (0.02)us-gaap_IncomeLossFromContinuingOperationsPerBasicShare |  | (0.50)us-gaap_IncomeLossFromContinuingOperationsPerBasicShare |
Net (loss) income from discontinued operations | (0.01)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare |  | 2.41 us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare |
Net income (loss) (in CAD per share) | (0.03)us-gaap_EarningsPerShareBasic |  | 1.91 us-gaap_EarningsPerShareBasic |
Dilutive effect of stock options (in shares) | 0 us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements |  | 342,957 us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements |
Weighted average number of shares outstanding, diluted |  |  |  |
Weighted average number of diluted common shares (in shares) | 35,014,418 us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding |  | 36,612,953 us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding |
Diluted per share information |  |  |  |
Net loss from continuing operations (in CAD per share) | (0.02)us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare |  | (0.50)us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare |
Net (loss) income from discontinued operations | (0.01)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare |  | 2.39 us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare |
Net income (loss) (in CAD per share) | (0.03)us-gaap_EarningsPerShareDiluted |  | 1.89 us-gaap_EarningsPerShareDiluted |
Share option plan |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Issued upon exercise of stock options (shares) | 385,880 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = noa_ShareOptionPlanMember | [1] | 295,230 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = noa_ShareOptionPlanMember | [1]
Senior executive stock option plan |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Issued upon exercise of stock options (shares) | 291,800 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = noa_SeniorExecutiveStockOptionPlanMember |  | 0 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = noa_SeniorExecutiveStockOptionPlanMember |
Treasury shares |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance, outstanding (shares) | 0 us-gaap_CommonStockSharesOutstanding / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember |  |  |
Purchase of treasury shares for settlement of certain equity classified stock-based compensation | (589,892)us-gaap_TreasuryStockSharesAcquired / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember |  |  |
Ending balance, outstanding (shares) | (589,892)us-gaap_CommonStockSharesOutstanding / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember |  |  |
[1] | All stock options exercised resulted in new common shares being issued (note 17(a))

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