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

No definition available.

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=116856206&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.

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- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

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Stock-based Compensation (Share Units Plan) (Details) - Share Units Plan [Member] - CAD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
PSU-ROIC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years in the plan period over which the units will vest	3 years
PSU-ROIC [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSU-ROIC [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
PSU-TSR [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years in the plan period over which the units will vest	3 years
PSU-TSR [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	0.00%
PSU-TSR [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	200.00%
Equity Settled Awards [Member] \| PSU-ROIC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested during the period	$ 45	$ 42	$ 43
Settlement from the Share Trusts in next fiscal year (in shares)	0.4
Equity Settled Awards [Member] \| PSU-ROIC [Member] \| 2017 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	169.00%
Equity Settled Awards [Member] \| PSU-TSR [Member] \| 2017 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting factor	100.00%