Commitments - Additional Information (Detail) - CAD CAD in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Commitments [Abstract]
Premises rental expense	CAD 178.1	CAD 165.0
Sublease rental income	7.4	6.0
Future minimum sublease payments expected to be received under noncancellable sublease agreements	CAD 16.8	CAD 20.9

The amount of future minimum sublease payments expected to be received under non-cancellable subleases for operating leases. Minimum lease payments are payments over the lease term that the lessee is, or can be, required to make, excluding contingent rent, costs for services and taxes to be paid by, and reimbursed to, the lessor, together with: (a) for a lessee, any amounts guaranteed by the lessee or by a party related to the lessee; or (b) for a lessor, any residual value guaranteed to the lessor by: (i) the lessee; (ii) a party related to the lessee; or (iii) a third party unrelated to the lessor that is financially capable of discharging the obligations under the guarantee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2017-01-01
-Paragraph 35
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2017-03-02&anchor=para_35_b&doctype=Standard&book=B
-URIDate 2017-03-09

Name:	ifrs-full_ExpectedFutureMinimumSubleasePaymentsReceivableUnderNoncancellableSubleasesClassifiedAsOperatingLease
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant