XML 67 R79.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2

Financial instruments and risk management - Risk management (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Customer 1 | Accounts receivable and contract assets | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	36.00%	16.00%
Customer 2 | Accounts receivable and contract assets | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	25.00%	8.00%
Customer 3 | Accounts receivable and contract assets | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%	33.00%
Customer 4 | Accounts receivable and contract assets | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	12.00%
Credit facilities
Concentration Risk [Line Items]
Outstanding balance, long-term debt	$ 190.0	$ 194.9
Basis on variable rate, adjustment	1.00%
Corresponding change in annual interest expense	$ 1.9

X

- Definition

Debt Instrument, Basis Spread on Variable Rate, Adjustment

+ References

No definition available.

+ Details

Name:	noa_DebtInstrumentBasisSpreadonVariableRateAdjustment
Namespace Prefix:	noa_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Interest Expense, Adjustment due to Interest Rate Change

+ References

No definition available.

+ Details

Name:	noa_InterestExpenseAdjustmentduetoInterestRateChange
Namespace Prefix:	noa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- 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_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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtPercentageBearingVariableInterestAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	srt_MajorCustomersAxis=noa_CustomerFMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=noa_AccountsReceivableAndContractwithCustomerAssetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=noa_CustomerGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=noa_CustomerHMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=noa_CustomerIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: