Pensions and other postretirement benefits (Details 11) - CAD	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pensions [Member]
Defined contribution and other plans disclosure [Line Items]
Employer's contributions	CAD 18,000,000	CAD 16,000,000	CAD 13,000,000

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

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration