Stock-based compensation - Options by exercise price range (Details) - Share option plan - CAD / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Number (in shares)	1,448,000
Options outstanding, Weighted average remaining life	5 years 5 months	6 years 1 month
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 5.33	CAD 5.87
Options exercisable	886,220	824,720
Options exercisable, Weighted average remaining life	4 years 7 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 6.52	CAD 8.41
$2.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 2.75
Options outstanding, Number (in shares)	288,900
Options outstanding, Weighted average remaining life	6 years 5 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 2.75
Options exercisable, Number (in shares)	149,420
Options exercisable, Weighted average remaining life	6 years 6 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 2.75
$2.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 2.79
Options outstanding, Number (in shares)	450,000
Options outstanding, Weighted average remaining life	6 years 6 months 12 days
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 2.79
Options exercisable, Number (in shares)	150,000
Options exercisable, Weighted average remaining life	6 years 6 months 12 days
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 2.79
$3.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 3.69
Options outstanding, Number (in shares)	29,100
Options outstanding, Weighted average remaining life	2 years 10 months 24 days
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 3.69
Options exercisable, Number (in shares)	29,100
Options exercisable, Weighted average remaining life	2 years 10 months 24 days
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 3.69
$4.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 4.90
Options outstanding, Number (in shares)	40,000
Options outstanding, Weighted average remaining life	6 years 3 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 4.90
Options exercisable, Number (in shares)	24,000
Options exercisable, Weighted average remaining life	6 years 3 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 4.90
$5.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 5.00
Options outstanding, Number (in shares)	127,760
Options outstanding, Weighted average remaining life	4 months 18 days
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 5.00
Options exercisable, Number (in shares)	127,760
Options exercisable, Weighted average remaining life	4 months 18 days
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 5.00
$5.91
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 5.91
Options outstanding, Number (in shares)	149,200
Options outstanding, Weighted average remaining life	8 years
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 5.91
Options exercisable, Number (in shares)	59,680
Options exercisable, Weighted average remaining life	8 years
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 5.91
$6.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 6.56
Options outstanding, Number (in shares)	79,860
Options outstanding, Weighted average remaining life	5 years 11 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 6.56
Options exercisable, Number (in shares)	63,080
Options exercisable, Weighted average remaining life	5 years 11 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 6.56
$8.28
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 8.28
Options outstanding, Number (in shares)	10,000
Options outstanding, Weighted average remaining life	3 years 6 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 8.28
Options exercisable, Number (in shares)	10,000
Options exercisable, Weighted average remaining life	3 years 6 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 8.28
$8.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 8.58
Options outstanding, Number (in shares)	30,000
Options outstanding, Weighted average remaining life	4 years 8 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 8.58
Options exercisable, Number (in shares)	30,000
Options exercisable, Weighted average remaining life	4 years 8 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 8.58
$9.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 9.33
Options outstanding, Number (in shares)	59,780
Options outstanding, Weighted average remaining life	4 years 1 month
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 9.33
Options exercisable, Number (in shares)	59,780
Options exercisable, Weighted average remaining life	4 years 1 month
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 9.33
$10.13
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 10.13
Options outstanding, Number (in shares)	59,060
Options outstanding, Weighted average remaining life	5 years
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 10.13
Options exercisable, Number (in shares)	59,060
Options exercisable, Weighted average remaining life	5 years
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 10.13
$13.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 13.50
Options outstanding, Number (in shares)	74,340
Options outstanding, Weighted average remaining life	1 year 11 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 13.50
Options exercisable, Number (in shares)	74,340
Options exercisable, Weighted average remaining life	1 year 11 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 13.50
$16.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	CAD 16.46
Options outstanding, Number (in shares)	50,000
Options outstanding, Weighted average remaining life	2 years 3 months
Options outstanding, Weighted average exercise price (in CAD per share)	CAD 16.46
Options exercisable, Number (in shares)	50,000
Options exercisable, Weighted average remaining life	2 years 3 months
Options exercisable, Weighted average exercise price (in CAD per share)	CAD 16.46

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price

No definition available.

Name:	noa_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePrice
Namespace Prefix:	noa_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=noa_ShareOptionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_TwoPointSeventyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_TwoPointSeventyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_ThreePointSixtyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_FourPointNinetyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_FivePointZeroMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_FivePointNinetyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_SixPointFiveSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_EightPointTwentyEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_EightPointFiftyEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_NinePointThrirtyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_TenPointTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_ThirteenPointFiftyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=noa_SixteenPointFortySixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: