The amount of the exposure to credit risk on loan commitments and financial guarantee contracts. [Refer: Loan commitments [member]; Financial guarantee contracts [member]; Credit risk [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35H
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35H&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35I
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35I&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35M
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35M&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Decommissioning and Other Provisions - Decommissioning and Restoration (Details) CAD in Millions, $ in Millions	Dec. 31, 2017 CAD	Dec. 31, 2016 CAD	Dec. 31, 2016 USD ($)
Disclosure of detailed information about borrowings [line items]
Undiscounted cash flows required for future removal of facilities	CAD 1,000
Centralia Coal Mine \| Surety Bonds
Disclosure of detailed information about borrowings [line items]
Bonds issued	139		$ 139
Alberta Mine \| Letters Of Credit [Member]
Disclosure of detailed information about borrowings [line items]
Bonds issued	CAD 120	CAD 117