Segmented Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 CAD ($) segment	Dec. 31, 2018 CAD ($)	Dec. 31, 2017 CAD ($)
Revenues from External Customers [Line Items]
Number of operating segments \| segment	1
Approximate percentage of the Company's freight revenues from national accounts	95.00%
Revenues	$ 14,917	$ 14,321	$ 13,041
Net income	4,216	4,328	5,484
Properties	39,669
Properties		37,773
Canada [Member]
Revenues from External Customers [Line Items]
Revenues	10,167	9,610	8,794
Net income	3,131	3,163	2,857
Properties	21,482
Properties		19,737
U.S. [Member]
Revenues from External Customers [Line Items]
Revenues	4,750	4,711	4,247
Net income	1,085	1,165	2,627
Properties	18,187
Properties		18,036
Freight [Member]
Revenues from External Customers [Line Items]
Revenues	$ 14,198	$ 13,548	$ 12,293
Revenue Benchmark [Member] \| Freight [Member] \| Customer Concentration Risk [Member]
Revenues from External Customers [Line Items]
Concentration of risk	3.00%	3.00%	3.00%

Approximate percentage of company's freight revenues from national accounts.

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Property, Plant, And Equipment And Finance Lease Right-of-Use Asset, After Accumulated Depreciation And Amortization

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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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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