Revenues - Disaggregation of Revenue (Details) - CAD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,964	$ 1,882	$ 5,678	$ 5,264
Leasing revenues	15	16	45	46
Total revenues	1,979	1,898	5,723	5,310
Freight [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,932	1,854	5,589	5,188
Total revenues	1,932	1,854	5,589	5,188
Grain
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	409	384	1,211	1,113
Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	183	171	514	486
Potash
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	117	130	367	358
Fertilizers and sulphur
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	55	186	171
Forest products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	78	76	229	211
Energy, chemicals and plastics
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	382	339	1,043	874
Metals, minerals and consumer products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	201	208	579	595
Automotive
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87	85	267	247
Intermodal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	409	406	1,193	1,133
Non-freight
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	32	28	89	76
Total revenues	$ 47	$ 44	$ 134	$ 122

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.

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Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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