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Shares - Share Purchase Program (Details) (CAD)
In Thousands, except Share data, unless otherwise specified
0 Months Ended 12 Months Ended
Dec. 18, 2014
Dec. 31, 2014
Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items]      
Retired through Share Purchase Program (shares)   500,000noa_StockRepurchaseProgramNumberofSharestobePurchasedandRetired 1,800,000noa_StockRepurchaseProgramNumberofSharestobePurchasedandRetired
Stock purchase program      
Equity, Class of Treasury Stock [Line Items]      
Retired through Share Purchase Program (shares) 1,771,195noa_StockRepurchaseProgramNumberofSharestobePurchasedandRetired
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
   
Percentage of issued and outstanding common shares purchased under Purchase Program 5.00%noa_StockRepurchaseProgramCommonVotingSharesPurchasedPercentage
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
   
Shares retired during period   500,000us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
1,800,000us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
Shares retired during period, percentage of issued and outstanding shares     5.00%noa_StockRepurchasedandRetiredDuringPeriodPercentageofIssuedandOutstandingShares
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
Common stock | Stock purchase program      
Equity, Class of Treasury Stock [Line Items]      
Increase (decrease) as a result of the retirement of shares   (4,238)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
(16,133)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
Additional paid in capital | Stock purchase program      
Equity, Class of Treasury Stock [Line Items]      
Increase (decrease) as a result of the retirement of shares   2,297us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
4,393us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_ShareRepurchaseProgramAxis
= noa_StockPurchaseProgramMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember