XML 24 R92.htm IDEA: XBRL DOCUMENT v2.4.0.6

Stock-based compensation - Options by exercise price range (Details) (Share option plan, CAD)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding	2,985,722
Options outstanding, weighted average remaining life	7 years 1 month 6 days	6 years 3 months 18 days
Options outstanding, weighted average exercise price	5.72
Number of options exercisable	1,122,362	1,031,774
Options exercisable, weighted average remaining life	4 years 2 months 12 days
Options exercisable, weighted average exercise price	8.82	8.82
$2.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	2.75
Number of options outstanding	705,600
Options outstanding, weighted average remaining life	9 years 6 months
Options outstanding, weighted average exercise price	2.75
Number of options exercisable	0
Options exercisable, weighted average remaining life	0 years
Options exercisable, weighted average exercise price	0.00
$2.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	2.79
Number of options outstanding	750,000
Options outstanding, weighted average remaining life	9 years 2 months 12 days
Options outstanding, weighted average exercise price	2.79
Number of options exercisable	0
Options exercisable, weighted average remaining life	0 years
Options exercisable, weighted average exercise price	0.00
$3.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	3.69
Number of options outstanding	115,840
Options outstanding, weighted average remaining life	6 years 4 months 24 days
Options outstanding, weighted average exercise price	3.69
Number of options exercisable	91,700
Options exercisable, weighted average remaining life	6 years 7 months 6 days
Options exercisable, weighted average exercise price	3.69
$4.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	4.90
Number of options outstanding	40,000
Options outstanding, weighted average remaining life	9 years
Options outstanding, weighted average exercise price	4.90
Number of options exercisable	0
Options exercisable, weighted average remaining life	0 years
Options exercisable, weighted average exercise price	0.00
$5.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	5.00
Number of options outstanding	403,982
Options outstanding, weighted average remaining life	1 year 9 months 18 days
Options outstanding, weighted average exercise price	5.00
Number of options exercisable	403,982
Options exercisable, weighted average remaining life	1 year 9 months 18 days
Options exercisable, weighted average exercise price	5.00
$6.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	6.56
Number of options outstanding	188,260
Options outstanding, weighted average remaining life	8 years 1 month 6 days
Options outstanding, weighted average exercise price	6.56
Number of options exercisable	42,140
Options exercisable, weighted average remaining life	7 years 4 months 24 days
Options exercisable, weighted average exercise price	6.56
$8.28
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	8.28
Number of options outstanding	80,000
Options outstanding, weighted average remaining life	6 years 2 months 12 days
Options outstanding, weighted average exercise price	8.28
Number of options exercisable	48,000
Options exercisable, weighted average remaining life	6 years 2 months 12 days
Options exercisable, weighted average exercise price	8.28
$8.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	8.58
Number of options outstanding	60,000
Options outstanding, weighted average remaining life	7 years 6 months
Options outstanding, weighted average exercise price	8.58
Number of options exercisable	24,000
Options exercisable, weighted average remaining life	7 years 6 months
Options exercisable, weighted average exercise price	8.58
$9.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	9.33
Number of options outstanding	125,560
Options outstanding, weighted average remaining life	6 years 6 months
Options outstanding, weighted average exercise price	9.33
Number of options exercisable	79,200
Options exercisable, weighted average remaining life	6 years 7 months 6 days
Options exercisable, weighted average exercise price	9.33
$10.21
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	10.13
Number of options outstanding	128,780
Options outstanding, weighted average remaining life	7 years 4 months 24 days
Options outstanding, weighted average exercise price	10.13
Number of options exercisable	55,640
Options exercisable, weighted average remaining life	7 years 3 months 18 days
Options exercisable, weighted average exercise price	10.13
$13.21
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	13.21
Number of options outstanding	75,000
Options outstanding, weighted average remaining life	4 years 9 months 18 days
Options outstanding, weighted average exercise price	13.21
Number of options exercisable	75,000
Options exercisable, weighted average remaining life	4 years 9 months 18 days
Options exercisable, weighted average exercise price	13.21
$13.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	13.50
Number of options outstanding	194,940
Options outstanding, weighted average remaining life	4 years 7 months 6 days
Options outstanding, weighted average exercise price	13.50
Number of options exercisable	194,940
Options exercisable, weighted average remaining life	4 years 7 months 6 days
Options exercisable, weighted average exercise price	13.50
$15.37
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	15.37
Number of options outstanding	40,000
Options outstanding, weighted average remaining life	5 years
Options outstanding, weighted average exercise price	15.37
Number of options exercisable	40,000
Options exercisable, weighted average remaining life	5 years
Options exercisable, weighted average exercise price	15.37
$16.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	16.46
Number of options outstanding	50,000
Options outstanding, weighted average remaining life	5 years
Options outstanding, weighted average exercise price	16.46
Number of options exercisable	40,000
Options exercisable, weighted average remaining life	5 years
Options exercisable, weighted average exercise price	16.46
$16.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price (CAD per share)	16.75
Number of options outstanding	27,760
Options outstanding, weighted average remaining life	3 years 6 months
Options outstanding, weighted average exercise price	16.75
Number of options exercisable	27,760
Options exercisable, weighted average remaining life	3 years 6 months
Options exercisable, weighted average exercise price	16.75

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- 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

X

- 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

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_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- 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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 2: 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

X

- 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



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a, b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

X

- 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

X

- 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