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Financial instruments and risk management - Risk management (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Concentration Risk [Line Items]
General payment terms	30 days
Trade accounts receivables | Geographic concentration risk | Western Canada
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	92.00%
Customer A | Total revenues | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	29.00%	23.00%
Customer A | Accounts receivable and unbilled revenue | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	28.00%	13.00%
Customer B | Total revenues | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	22.00%	22.00%
Customer B | Accounts receivable and unbilled revenue | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	26.00%	21.00%
Customer C | Total revenues | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	14.00%
Customer C | Accounts receivable and unbilled revenue | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	17.00%	8.00%
Customer D | Total revenues | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%
Customer E | Total revenues | Major customers
Concentration Risk [Line Items]
Concentration risk, percentage	2.00%	10.00%

X

- Definition

Accounts Receivable, General Payment Terms

+ References

No definition available.

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- 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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13531-108611



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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