Financial Instruments And Risk Management - Financial Assets (Details) - CAD CAD in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives
Financial Assets Offsetting
Gross Assets	CAD 1,126	CAD 1,765
Gross Liabilities Offset	(1,052)	(1,610)
Net Amounts Presented	74	155
Trade receivables
Financial Assets Offsetting
Gross Assets	2,405	2,058
Gross Liabilities Offset	(1,252)	(946)
Net Amounts Presented	1,153	1,112
Financial assets
Financial Assets Offsetting
Gross Assets	3,531	3,823
Gross Liabilities Offset	(2,304)	(2,556)
Net Amounts Presented	CAD 1,227	CAD 1,267

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

+ Details

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

- Definition

The gross amount of recognised financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement. [Refer: Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 13C
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_13C_a&doctype=Standard
-URIDate 2017-03-09

+ Details

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

- Definition

The amount of financial liabilities set off against financial assets when an entity: (a) currently has a legally enforceable right to set off the recognised amounts; and (b) intends either to settle on a net basis or to realise the asset and settle the liability simultaneously. [Refer: Financial assets; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 13C
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_13C_b&doctype=Standard
-URIDate 2017-03-09

+ Details

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

- Definition

The net amount of financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement, presented in the statement of financial position. [Refer: Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 13C
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_13C_c&doctype=Standard
-URIDate 2017-03-09

+ Details

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

- Details

Name:	ifrs-full_TypesOfFinancialAssetsAxis=ifrs-full_DerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfFinancialAssetsAxis=ifrs-full_TradeReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfFinancialAssetsAxis=ifrs-full_FinancialAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: