Number of additional Performance Deferred Share Units that can be granted as a percentage of units originally granted

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Grant Date Fair Value

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Trading Days Used to Calculate Average Share Price

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No definition available.

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- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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-Name Accounting Standards Codification
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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.

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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).

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- Definition

Amount of cash paid to settle liability for award under share-based payment arrangement.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

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- Definition

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

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Value, before forfeiture, of shares granted under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

+ References

No definition available.

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Stock-Based Compensation - Narrative (Details) - CAD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 26		$ 56	$ 75	$ 110
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options issued				1,339,886
Weighted-average grant price				$ 87.64
Expiration period				7 years
Stock options grant date fair value				$ 26
Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				12 months
Stock Options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				48 months
Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued				431,430			626,400
Grant date fair value				$ 37
PSU payout percentage						200.00%
Number of trading days						30 days
Units paid in period		570,056
Cash payout		$ 98
Performance Share Units (PSUs) \| Retention Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued							184,875
PSU payout percentage						125.00%
Number of trading days	30 days
Units paid in period	169,272
Cash payout	$ 20
Performance Deferred Share Units (PDSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued				12,694
Grant date fair value				$ 1
Number of additional PDSUs that can be granted as a % of original units granted	25.00%			25.00%
PSUs and PDSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Deferred Share Units (DSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				36 months
Units issued				62,157
Grant date fair value				$ 6