Revenues - Disaggregation of Revenue (Details) - CAD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,777	$ 1,961	$ 3,806	$ 3,714
Leasing revenues	15	16	29	30
Total revenues	1,792	1,977	3,835	3,744
Freight
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,752	1,931	3,752	3,657
Total revenues	1,752	1,931	3,752	3,657
Grain
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	446	422	864	802
Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	131	173	281	331
Potash
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	146	136	258	250
Fertilizers and sulphur
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	77	63	147	120
Forest products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81	78	159	151
Energy, chemicals and plastics
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	341	346	832	661
Metals, minerals and consumer products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	133	205	322	378
Automotive
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	34	104	121	180
Intermodal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	363	404	768	784
Non-freight excluding leasing revenues
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 25	$ 30	$ 54	$ 57

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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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