Pensions and other postretirement benefits (Details 6) - CAD CAD in Millions	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in Consolidated Balance Sheet
Noncurrent assets - Pension asset	CAD 907	CAD 1,305
Current liabilities	(18)	(18)
Noncurrent liabilities - Pension and other postretirement benefits	(694)	(720)
Pensions [Member]
Amounts recognized in Consolidated Balance Sheet
Noncurrent assets - Pension asset	907	1,305
Current liabilities	0	0
Noncurrent liabilities - Pension and other postretirement benefits	(442)	(469)
Total amount recognized	465	836
Other postretirement benefits [Member]
Amounts recognized in Consolidated Balance Sheet
Noncurrent assets - Pension asset	0	0
Current liabilities	(18)	(18)
Noncurrent liabilities - Pension and other postretirement benefits	(252)	(251)
Total amount recognized	CAD (270)	CAD (269)

The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919

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-Publisher FASB
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- Definition

The amount for overfunded plans recognized in the balance sheet as a noncurrent asset associated with a defined benefit pension plan or other postretirement defined benefit plan.

+ References

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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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- Definition

For a classified balance sheet, the amount recognized in balance sheet as a current liability associated with an underfunded defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Current Liabilities
-URI http://asc.fasb.org/extlink&oid=6509677

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- Definition

This represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement defined benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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