Share-Based Compensation and Other Related Information - Summary of Options Outstanding (Parenthetical) (Detail) $ in Millions	12 Months Ended
Dec. 31, 2017 CAD ($)	Dec. 31, 2016 CAD ($)	Dec. 31, 2016 USD ($)
Disclosure of terms and conditions of share-based payment arrangement [abstract]
Stock option plans, vesting period		3 years
Stock option plans, exercisable		$ 20.27
Stock option plans, expiration period		2023
Grant date fair value of share options			$ 15
Weighted average share price of stock option exercised	$ 21.78	$ 20.74

Option vesting period.

No definition available.

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- Definition

Stock option expiration period.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

The exercise price of share options granted.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_47_a_i&doctype=Standard
-URIDate 2017-03-09

+ Details

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- Definition

The weighted average share price at the date of exercise for share options that are exercised in a share-based payment arrangement. [Refer: Share-based payment arrangements [member]; Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_c&doctype=Standard
-URIDate 2017-03-09

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- Definition

The weighted average fair value of share options granted during the period at the measurement date. [Refer: Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 47
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_47_a&doctype=Standard
-URIDate 2017-03-09

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