Earnings Per Share - Summary of Basic Earnings Per Share (Detail) - CAD ($) $ / shares in Units, $ in Millions	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018
Basic earnings per share [abstract]
Net income attributable to shareholders	$ 227.0	$ 238.9
Weighted average number of shares	98,291,845	106,961,014
Earnings per share - basic	$ 2.31	$ 2.23

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2018-01-01
-Paragraph 66
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2018-03-01&anchor=para_66&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_BasicEarningsLossPerShare
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	ifrs-full_BasicEarningsPerShareAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The profit (loss) from continuing and discontinued operations attributable to owners of the parent. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 81B
-Subparagraph a
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_81B_a_ii&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_ProfitLossAttributableToOwnersOfParent
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2018-01-01
-Paragraph 70
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2018-03-01&anchor=para_70_b&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_WeightedAverageShares
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration