XML 71 R51.htm IDEA: XBRL DOCUMENT v3.8.0.1

Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock-based compensation expenses included in general and administrative expenses

Stock-based compensation expenses included in general and administrative expenses are as follows:

Year ended December 31,		2017				2016
Share option plan (note 21(b))		$	326			$	587
Liability classified restricted share unit plan (note 21(c(i)))		—				52
Equity classified restricted share unit plan (note 21(c(ii)))		1,293				1,384
Equity performance restricted share unit plan (note 21(d))		1,306				820
Liability classified deferred stock unit plan (note 21(e))		1,070				3,187
		$	3,995			$	6,030

Schedule of stock options activity

		Number of options			Weighted average exercise price $ per share
Outstanding at December 31, 2015		1,448,000			5.33
Exercised(i)		(102,040	)		2.77
Forfeited		(169,880	)		5.31
Outstanding at December 31, 2016		1,176,080			5.56
Exercised(i)		(176,800	)		3.26
Forfeited		(85,740	)		12.36
Outstanding at December 31, 2017		913,540			5.36

(i) All stock options exercised resulted in new common shares being issued (note 17(a)).

Summary of information about stock options outstanding

The following table summarizes information about stock options outstanding at December 31, 2017:

		Options outstanding									Options exercisable
Exercise price		Number			Weighted average remaining life		Weighted average exercise price				Number			Weighted average remaining life		Weighted average exercise price
$2.75		187,420			4.3 years		$	2.75			187,420			4.3 years		$	2.75
$2.79		300,000			4.5 years		$	2.79			300,000			4.5 years		$	2.79
$3.69		25,800			0.9 years		$	3.69			25,800			0.9 years		$	3.69
$5.91		132,000			6.0 years		$	5.91			105,600			6.0 years		$	5.91
$6.56		70,780			3.9 years		$	6.56			70,780			3.9 years		$	6.56
$8.28		10,000			1.5 years		$	8.28			10,000			1.5 years		$	8.28
$8.58		30,000			2.7 years		$	8.58			30,000			2.7 years		$	8.58
$9.33		55,780			2.1 years		$	9.33			55,780			2.1 years		$	9.33
$10.13		51,760			3.0 years		$	10.13			51,760			3.0 years		$	10.13
$16.46		50,000			0.3 years		$	16.46			50,000			0.3 years		$	16.46
		913,540			4.0 years		$	5.36			887,140			3.9 years		$	5.35

Schedule of performance restricted share units

		Number of units			Weighted average exercise price $ per share
Outstanding at December 31, 2015		423,592			4.86
Granted		343,706			4.97
Forfeited		(27,998	)		4.52
Outstanding at December 31, 2016		739,300			4.84
Granted		248,824			5.98
Vested		(69,949	)		8.57
Forfeited		(21,542	)		4.05
Outstanding at December 31, 2017		896,633			4.81

Schedule of assumptions used in estimate of fair value

The Company estimated the fair value of the PSUs granted during the years ended December 31, 2017 and 2016 using a Monte Carlo simulation with the following assumptions:

		2017			2016
Risk-free interest rate		1.17	%		0.52	%
Expected volatility		46.47	%		43.30	%

Schedule of stock plan activity

		Number of units
Outstanding at December 31, 2015		928,874
Granted		171,980
Redeemed		(158,917	)
Outstanding at December 31, 2016		941,937
Granted		114,895
Redeemed		(65,249	)
Outstanding at December 31, 2017		991,583

Liability classified restricted share unit plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of restricted share unit plan activity

Liability classified restricted share unit plan

		Number of units
Outstanding at December 31, 2015		290,790
Vested		(290,790	)
Outstanding at December 31, 2016 and 2017		—

Equity classified restricted share unit plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of restricted share unit plan activity

Equity classified restricted share unit plan

		Number of units			Weighted average exercise price $ per share
Outstanding at December 31, 2015		774,156			4.45
Granted		501,523			3.78
Vested		(87,580	)		3.51
Forfeited		(64,124	)		3.50
Outstanding at December 31, 2016		1,123,975			4.20
Granted		355,292			6.02
Vested		(259,860	)		6.24
Forfeited		(29,474	)		4.00
Outstanding at December 31, 2017		1,189,933			4.22

X

- Definition

Tabular disclosure of the amount of total share-based compensation cost, including the amounts attributable to each share-based compensation plan and any related tax benefits.

+ 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 (h)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure for share-based compensation plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year.

+ 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)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of option exercise prices, by grouped ranges, including the upper and lower limits of the price range, the number of shares under option, weighted average exercise price and remaining contractual option terms.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value.

+ 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 (d)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.

+ 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 (f)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Details

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