Resulting performance vesting factor from the return on investment level obtained.

No definition available.

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- Definition

Cash settlement for share-based compensation during the period.

+ References

No definition available.

+ Details

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- Definition

Number of units to be settled from the Share Trusts in the next fiscal year.

+ References

No definition available.

+ Details

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- Definition

The payout to be paid in the first quarter of the next fiscal year due to conditions of cash settled performance share units being met.

+ References

No definition available.

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- Definition

The number of units of cash settled stock-based compensation awards modified in 2014 to settle in common shares of the Company.

+ References

No definition available.

+ Details

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- Definition

Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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 (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- 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

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- Definition

An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

+ 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)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

The number of employees affected by the modification of an equity-based compensation plan.

+ 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)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:integerItemType
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Stock-based compensation (Narrative) (Details 2) - CAD shares in Millions, CAD in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments Related to Tax Withholding for Share-based Compensation	CAD 44	CAD 2	CAD 0
PSUs-ROIC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected by modification to stock-based compensation plan	133
PSUs-ROIC \| Minimum [Member] \| 2013 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-ROIC \| Minimum [Member] \| 2014 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-ROIC \| Minimum [Member] \| 2015 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-ROIC \| Minimum [Member] \| 2016 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-ROIC \| Maximum [Member] \| 2013 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	150.00%
PSUs-ROIC \| Maximum [Member] \| 2014 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	150.00%
PSUs-ROIC \| Maximum [Member] \| 2015 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
PSUs-ROIC \| Maximum [Member] \| 2016 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
PSUs-TSR \| Minimum [Member] \| 2015 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-TSR \| Minimum [Member] \| 2016 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSUs-TSR \| Maximum [Member] \| 2015 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
PSUs-TSR \| Maximum [Member] \| 2016 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
DSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted during the period (in shares)	0.2
Payments Related to Tax Withholding for Share-based Compensation	CAD 16
Equity settled awards \| PSUs-ROIC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Settlement from the Share Trusts, next fiscal year	0.3
Payments Related to Tax Withholding for Share-based Compensation	CAD 25
Equity settled awards \| PSUs-ROIC \| 2013 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested during the period		48
Equity settled awards \| PSUs-ROIC \| 2014 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	150.00%
Fair value of awards vested during the period	CAD 41
Cash settled awards \| 2013 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested during the period		39
Cash settled awards \| PSUs-ROIC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted during the period (in shares)	0.8
Cash settled awards \| PSUs-ROIC \| 2012 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested during the period			CAD 106
Cash settled awards \| PSUs-ROIC \| 2014 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash settled awards modified to equity settled awards			0.4
Performance vesting factor	150.00%
Fair value of awards vested during the period	CAD 45
Share Units Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental compensation cost from modification	CAD 0
Share Units Plan \| PSUs-ROIC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The number of years in the plan period over which the units will vest	3 years
Share Units Plan \| PSUs-TSR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The number of years in the plan period over which the units will vest	3 years
Share Units Plan \| Cash settled awards \| PSUs-ROIC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout related to cash settled PSUs in the first quarter of next fiscal year	CAD 45	CAD 37
Units granted during the period (in shares)	0.0
Cash paid out for the awards	CAD 37
Share Units Plan \| Cash settled awards \| PSUs-ROIC \| 2013 grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash settled awards modified to equity settled awards			0.5