Long-term debt (Maturities) (Details) - CAD CAD in Millions	Dec. 31, 2017	Dec. 31, 2016
Capital Leases
2018	CAD 44
2019	10
2020	15
2021	6
2022	2
2023 and thereafter	81
Total capital leases	158
Debt
2018	2,036
2019	684
2020	0
2021	747
2022	308
2023 and thereafter	6,895
Total debt	10,670
Total
2018	2,080
2019	694
2020	15
2021	753
2022	310
2023 and thereafter	6,976
Total	CAD 10,828	CAD 10,937

Amount of minimum lease payments for capital leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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