Other long-term liabilities and deferred credits - Changes in Environmental Remediation Obligation (Details) - CAD CAD in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Accrual for Environmental Loss Contingencies [Roll Forward]
Opening Balance	CAD 70,072	CAD 69,555
Remediation activities	(10,621)	(12,739)
Accretion	2,147	2,273
Changes in cash flow estimates	3,171	268
Revision in assumptions	(5,843)	1,954
Purchase price adjustment	0	2,726
Foreign exchange rate adjustment	12,603	6,035
Closing Balance	CAD 71,529	CAD 70,072

Accrual for Environmental Loss Contingencies, Accretion

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- Definition

Accrual for Environmental Loss Contingencies, Increase (Decrease) for Revision in Assumptions

+ References

No definition available.

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- Definition

Accrual for Environmental Loss Contingencies, Remediation Activities

+ References

No definition available.

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

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- Definition

The Increase or Decrease in the accrual for environmental loss contingencies in the period arising from business acquisitions or divestitures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.Y.Q2)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

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- Definition

The Increase or Decrease in the accrual for environmental loss contingencies during the reporting period related to currency translations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Foreign Currency Translation
-URI http://asc.fasb.org/extlink&oid=6513664

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (SAB TOPIC 5.Y.Q2)
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- Definition

The Increase or Decrease in the accrual for environmental loss in the period from revisions in estimates to existing obligations. The amount does not relate to changes in the environmental accrual related to business acquisitions or divestitures, or to currency movements.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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