Canadian Pacific Railway Limited (CP) 10-K 18 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 17, 2021	Jun. 30, 2020
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Document Period End Date	Dec. 31, 2020
Entity Registrant Name	CANADIAN PACIFIC RAILWAY LTD/CN
Entity Central Index Key	0000016875
Entity File Number	001-01342
Entity Tax Identification Number	98-0355078
Entity Incorporation, State or Country Code	Z4
Entity Address, Address Line One	7550 Ogden Dale Road S.E.
Entity Address, City or Town	Calgary
Entity Address, State or Province	AB
Entity Address, Postal Zip Code	T2C 4X9
City Area Code	(403)
Local Phone Number	319-7000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 34,600,245,541
Entity Common Stock, Shares Outstanding		133,297,236
Common Shares, without par value, of Canadian Pacific Railway Limited
Entity Information [Line Items]
Title of 12(b) Security	Common Shares, without par value, of Canadian Pacific Railway Limited
Trading Symbol	CP
Security Exchange Name	NYSE
Perpetual 4% Consolidated Debenture Stock of Canadian Pacific Railway Company
Entity Information [Line Items]
Title of 12(b) Security	Perpetual 4% Consolidated Debenture Stock of Canadian Pacific Railway Company
Trading Symbol	CP/40
Security Exchange Name	NYSE

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - CAD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues
Total revenues	$ 7,710	$ 7,792	$ 7,316
Operating expenses
Compensation and benefits	1,560	1,540	1,468
Fuel	652	882	918
Materials	216	210	201
Equipment rents	142	137	130
Depreciation and amortization	779	706	696
Purchased services and other	1,050	1,193	1,072
Total operating expenses	4,399	4,668	4,485
Operating income	3,311	3,124	2,831
Less:
Other expense (income)	(7)	(89)	174
Other components of net periodic benefit recovery	(342)	(381)	(384)
Net interest expense	458	448	453
Income before income tax expense	3,202	3,146	2,588
Income tax expense	758	706	637
Net income	$ 2,444	$ 2,440	$ 1,951
Earnings per share
Basic earnings per share	$ 18.05	$ 17.58	$ 13.65
Diluted earnings per share	$ 17.97	$ 17.52	$ 13.61
Weighted-average number of shares (millions)
Basic	135.5	138.8	142.9
Diluted	136	139.3	143.3
Freight
Revenues
Total revenues	$ 7,541	$ 7,613	$ 7,152
Non-freight
Revenues
Total revenues	$ 169	$ 179	$ 164

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 2,444	$ 2,440	$ 1,951
Net gain (loss) in foreign currency translation adjustments, net of hedging activities	18	37	(60)
Change in derivatives designated as cash flow hedges	9	10	38
Change in pension and post-retirement defined benefit plans	(407)	(661)	(449)
Other comprehensive loss before income taxes	(380)	(614)	(471)
Income tax recovery on above items	88	135	169
Other comprehensive income (loss)	(292)	(479)	(302)
Comprehensive income	$ 2,152	$ 1,961	$ 1,649

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 147	$ 133
Accounts receivable, net	825	805
Materials and supplies	208	182
Other current assets	141	90
Total current assets	1,321	1,210
Investments	199	341
Properties	20,422	19,156
Goodwill and intangible assets	366	206
Pension asset	894	1,003
Other assets	438	451
Total assets	23,640	22,367
Current liabilities
Accounts payable and accrued liabilities	1,467	1,693
Long-term debt maturing within one year	1,186	599
Total current liabilities	2,653	2,292
Pension and other benefit liabilities	832	785
Other long-term liabilities	585	562
Long-term debt	8,585	8,158
Deferred income taxes	3,666	3,501
Total liabilities	16,321	15,298
Shareholders’ equity
Share capital	1,983	1,993
Additional paid-in capital	55	48
Accumulated other comprehensive loss	(2,814)	(2,522)
Retained earnings	8,095	7,550
Total shareholders' equity	7,319	7,069
Total liabilities and shareholders’ equity	$ 23,640	$ 22,367

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, shares authorized	Unlimited	Unlimited
Common stock, shares issued	133.3	137
Common stock, shares outstanding	133.3	137
First preferred stock, shares authorized	Unlimited	Unlimited
Second preferred stock, shares authorized	Unlimited	Unlimited

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 2,444	$ 2,440	$ 1,951
Reconciliation of net income to cash provided by operating activities:
Depreciation and amortization	779	706	696
Deferred income tax expense	221	181	256
Pension recovery and funding	(250)	(360)	(321)
Foreign exchange (gain) loss on debt and lease liabilities	(14)	(94)	168
Settlement of forward starting swaps on debt issuance	0	0	(24)
Other operating activities, net	11	143	(79)
Change in non-cash working capital related to operations	(389)	(26)	65
Cash provided by operating activities	2,802	2,990	2,712
Investing activities
Additions to properties	(1,671)	(1,647)	(1,551)
Investment in Detroit River Tunnel Partnership	(398)	0	0
Investment in Central Maine & Quebec Railway	19	(174)	0
Proceeds from sale of properties and other assets	22	26	78
Other investing activities	(2)	(8)	15
Cash used in investing activities	(2,030)	(1,803)	(1,458)
Financing activities
Dividends paid	(467)	(412)	(348)
Issuance of CP Common Shares	52	26	24
Purchase of CP Common shares	(1,509)	(1,134)	(1,103)
Issuance of long-term debt, excluding commercial paper	958	397	638
Repayment of long-term debt, excluding commercial paper	(84)	(500)	(753)
Net issuance of commercial paper	270	524	0
Net increase in short-term borrowings	5	0	0
Other financing activities	11	(12)	0
Cash used in financing activities	(764)	(1,111)	(1,542)
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	6	(4)	11
Cash position
Increase (decrease) in cash and cash equivalents	14	72	(277)
Cash and cash equivalents at beginning of year	133	61	338
Cash and cash equivalents at end of year	147	133	61
Supplemental disclosures of cash flow information:
Income taxes paid	582	506	318
Interest paid	$ 443	444	$ 463
CMQ
Investing activities
Investment in Detroit River Tunnel Partnership		$ (174)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - CAD ($) $ in Millions	Total	Share capital	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings	Cumulative Effect, Period of Adoption, Adjusted Balance	Cumulative Effect, Period of Adoption, Adjusted BalanceRetained earnings
Beginning balance at Dec. 31, 2017	$ 6,437	$ 2,032	$ 43	$ (1,741)	$ 6,103
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,951	0	0	0	1,951
Other comprehensive (loss) income	(302)	0	0	(302)	0
Dividends declared	(358)	0	0	0	(358)
Effect of stock-based compensation expense	11	0	11	0	0
CP Common Shares repurchased	(1,127)	(66)	0	0	(1,061)
Shares issued under stock option plan	24	36	(12)	0	0
Ending balance at Dec. 31, 2018	6,636	2,002	42	(2,043)	6,635
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at January 1, as restated		2,002	42	(2,043)		$ 6,631	$ 6,630
Net income	2,440	0	0	0	2,440
Other comprehensive (loss) income	(479)	0	0	(479)	0
Dividends declared	(434)	0	0	0	(434)
Effect of stock-based compensation expense	15	0	15	0	0
CP Common Shares repurchased	(1,140)	(54)	0	0	(1,086)
Shares issued under stock option plan	36	45	(9)	0	0
Ending balance at Dec. 31, 2019	7,069	1,993	48	(2,522)	7,550
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at January 1, as restated		1,993	48	(2,522)		$ 7,068	$ 7,549
Net income	2,444	0	0	0	2,444
Other comprehensive (loss) income	(292)	0	0	(292)	0
Dividends declared	(479)	0	0	0	(479)
Effect of stock-based compensation expense	17	0	17	0	0
CP Common Shares repurchased	(1,477)	(58)	0	0	(1,419)
Shares issued under stock option plan	38	48	(10)	0	0
Ending balance at Dec. 31, 2020	$ 7,319	$ 1,983	$ 55	$ (2,814)	$ 8,095

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per share	$ 0.9500	$ 3.5600	$ 3.1400	$ 2.5125

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Nature of Operations	Canadian Pacific Railway Limited (“CPRL”), through its subsidiaries (collectively referred to as “CP” or “the Company”), operates a transcontinental railway in Canada and the United States ("U.S."). CP provides rail and intermodal transportation services over a network of approximately 13,000 miles, serving the principal business centres of Canada from Montréal, Québec, to Vancouver, British Columbia, and the U.S. Northeast and Midwest regions. CP’s railway network feeds directly into the U.S. heartland from the East and West coasts. Agreements with other carriers extend the Company’s market reach in Canada, throughout the U.S. and into Mexico. CP transports bulk commodities, merchandise freight and intermodal traffic. Bulk commodities include grain, coal, fertilizers and sulphur. Merchandise freight consists of finished vehicles and automotive parts, as well as forest, industrial and consumer products. Intermodal traffic consists largely of retail goods in overseas containers that can be transported by train, ship and truck, and in domestic containers and trailers that can be moved by train and truck.
Summary of Significant Accounting Policies	Summary of significant accounting policies Accounting principles generally accepted in the United States of America (“GAAP”) These Consolidated Financial Statements are expressed in Canadian dollars and have been prepared in accordance with GAAP. Principles of consolidation These Consolidated Financial Statements include the accounts of CP and all its subsidiaries. The Company’s investments in which it has significant influence are accounted for using the equity method. Distributions received from equity method investees are classified using the nature of the distribution approach for cash flow presentation purposes, whereby distributions received are classified based on the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities). All intercompany accounts and transactions have been eliminated. Use of estimates The preparation of these Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of revenues and expenses during the year, the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements. Management regularly reviews its estimates, including those related to environmental liabilities, pensions and other benefits, depreciable lives of properties, deferred income tax assets and liabilities, as well as legal and personal injury liabilities based upon currently available information. Actual results could differ from these estimates. Revenue recognition Revenue is recognized when obligations under the terms of a contract with a customer are satisfied. Revenue is measured as the amount of consideration the Company expects to receive in exchange for providing services. Government imposed taxes that the Company collects concurrent with revenue generating activities are excluded from revenue. In the normal course of business, the Company does not generate any material revenue through acting as an agent for other entities. The Company provides rail freight transportation services to a wide variety of customers and transports bulk commodities, merchandise freight and intermodal traffic. The Company signs master service agreements with customers that dictate future services the Company is to perform for a customer at the time a bill of lading or service request is received. Each bill of lading or service request represents a separate distinct performance obligation that the Company is obligated to satisfy. The transaction price is generally in the form of a fixed fee determined at the inception of the bill of lading or service request. The Company allocates the transaction price to each distinct performance obligation based on the estimated standalone selling price for each performance obligation. As each bill of lading or service request represents a separate distinct performance obligation, the estimated standalone selling price is assessed at an observable price which is fair market value. Certain customer agreements include variable consideration in the form of rebates, discounts, or incentives. The expected value method is used to estimate variable consideration and is allocated to the applicable performance obligation and is recognized when the related performance obligation is satisfied. Additionally, the Company offers published rates for services through public tariff agreements in which a customer can request service, triggering a performance obligation the Company must satisfy. Railway freight revenues are recognized over time as services are provided based on the percentage of completed service method. Volume rebates to customers are accrued as a reduction of freight revenues based on estimated volumes and contract terms as freight service is provided. Freight revenues also include certain ancillary and other services provided in association with the performance of rail freight movements. Revenues from these activities are not material and therefore have been aggregated with the freight revenues from customer contracts with which they are associated. Non-freight revenues, including revenues earned from passenger service operators, switching fees, and revenues from logistics services, are recognized at the point in time the services are provided or when the performance obligations are satisfied. Non-freight revenues also include leasing revenues. Payment by customers is due upon satisfaction of performance obligations. Payment terms are such that amounts outstanding at the period end are expected to be collected within one reporting period. The Company invoices customers at the time the bill of lading or service request is processed and therefore the Company has no material unbilled receivables and no contract assets. All performance obligations not fully satisfied at period end are expected to be satisfied within the reporting period immediately following. Contracted customer incentives are amortized to income over the term of the related revenue contract. Income taxes The Company follows the liability method of accounting for income taxes. Deferred income tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The effect of a change in income tax rates on deferred income tax assets and liabilities is recognized in income in the period during which the change occurs. When appropriate, the Company records a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, CP considers whether it is more likely than not that all or some portion of CP’s deferred tax assets will not be realized, based on management’s judgment using available evidence about future events. At times, tax benefit claims may be challenged by a tax authority. Tax benefits are recognized only for tax positions that are more likely than not sustainable upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for “unrecognized tax benefits” is recorded for any tax benefits claimed in CP’s tax returns that do not meet these recognition and measurement standards. Investment and other similar tax credits are deferred on the Company's Consolidated Balance Sheets and amortized to “Income tax expense” as the related asset is recognized in income. Income tax recovery or expense on items in "Accumulated other comprehensive loss" are recognized in "Income tax expense" as the related item is recognized in income. Earnings per share Basic earnings per share are calculated using the weighted-average number of the Company's Common Shares ("Common Shares") outstanding during the year. Diluted earnings per share are calculated using the treasury stock method for determining the dilutive effect of options. Foreign currency translation Assets and liabilities denominated in foreign currencies, other than those held through foreign subsidiaries, are translated into Canadian dollars at the year-end exchange rate for monetary items and at the historical exchange rates for non-monetary items. Foreign currency revenues and expenses are translated at the exchange rates in effect on the dates of the related transactions. Foreign exchange ("FX") gains and losses, other than those arising from the translation of the Company’s net investment in foreign subsidiaries, are included in income. The accounts of the Company’s foreign subsidiaries are translated into Canadian dollars using the year-end exchange rate for assets and liabilities and the average exchange rates during the year for revenues, expenses, gains, and losses. FX gains and losses arising from the translation of the foreign subsidiaries’ assets and liabilities are included in “Other comprehensive loss”. A portion of U.S. dollar-denominated long-term debt has been designated as a hedge of the net investment in foreign subsidiaries. As a result, unrealized FX gains and losses on U.S. dollar-denominated long-term debt, designated as a hedge, are offset against FX gains and losses arising from the translation of foreign subsidiaries’ accounts in “Other comprehensive loss”. Cash and cash equivalents Cash and cash equivalents include highly liquid short-term investments that are readily convertible to cash with original maturities of three months or less, but excludes cash and cash equivalents subject to restrictions. Accounts receivable Accounts receivable from customers are recognized initially at fair value and subsequently measured at amortized cost less allowance for expected credit losses. Losses on accounts receivable are estimated based on historical credit loss experience of receivables with similar risk characteristics. Historical loss experience is adjusted to reflect any management expectations that current or future conditions will differ from conditions that existed for the period over which historical information is evaluated. To determine expected credit losses, receivables are disaggregated by credit characteristics, type of customer service, customer line of business, and receivable aging. Receivables are considered to be in default and are written off against the allowance for credit losses when it is probable that all remaining contractual payments due will not be collected in accordance with the terms of the customer contracts. Subsequent recoveries of amounts previously written off are credited to earnings in the period recovered. Materials and supplies Materials and supplies are carried at the lower of average cost or market value and consist primarily of fuel and parts used in the repair and maintenance of track structures, equipment, locomotives and freight cars. Properties Fixed asset additions and major renewals are recorded at cost, including direct costs, attributable indirect costs and carrying costs, less accumulated depreciation and any impairment. When there is a legal obligation associated with the retirement of property, a liability, when reliably estimable, is initially recognized at its fair value and a corresponding asset retirement cost is added to the gross book value of the related asset and amortized to expense over the estimated term to retirement. The Company reviews the carrying amounts of its properties whenever changes in circumstances indicate that such carrying amounts may not be recoverable based on future undiscounted cash flows. When such properties are determined to be impaired, recorded asset values are revised to their fair value and an impairment loss is recognized. The Company recognizes expenditures as additions to properties or operating expenses based on whether the expenditures increase the output or service capacity, lower the associated operating costs or extend the useful life of the properties and whether the expenditures exceed minimum physical and financial thresholds. Much of the additions to properties, both new and replacement properties, are self-constructed. These are initially recorded at cost, including direct costs and attributable indirect costs, overheads and carrying costs. Direct costs include, among other things, labour costs, purchased services, equipment costs and material costs. Attributable indirect costs and overheads include incremental long-term variable costs resulting from the execution of capital projects. Indirect costs mainly include work trains, material distribution, highway vehicles and work equipment. Overheads primarily include a portion of the engineering department’s costs, which plans, designs and administers these capital projects. These costs are allocated to projects by applying a measure consistent with the nature of the cost, based on cost studies. For replacement properties, the project costs are allocated to dismantling and installation based on cost studies. Dismantling work, which is expensed, is performed concurrently with the installation. Ballast programs including undercutting, shoulder ballasting and renewal programs that form part of the annual track program are capitalized as this work, and the related added ballast material, significantly improves drainage, which in turn extends the life of ties and other track materials. These costs are tracked separately from the underlying assets and depreciated over the period to the next estimated similar ballast program. Spot replacement of ballast is considered a repair which is expensed as incurred. The costs of large refurbishments are capitalized and locomotive overhauls are expensed as incurred, except where overhauls represent a betterment of the locomotive in which case costs are capitalized. The Company capitalizes development costs for major new computer systems. The Company follows group depreciation, which groups assets which are similar in nature and have similar economic lives. The property groups are depreciated on a straight-line basis reflecting their expected economic lives determined by depreciation studies. Depreciation studies are regular reviews of asset service lives, salvage values, accumulated depreciation and other related factors. Depreciation rates are established through these studies. Actual use and retirement of assets may vary from current estimates, and would be identified in the next study. These changes in expected economic lives would impact the amount of depreciation expense recognized in future periods. All track assets are depreciated using a straight-line method which recognizes the value of the asset consumed as a percentage of the whole life of the asset. When depreciable property is retired or otherwise disposed of in the normal course of business, the book value, less net salvage proceeds, is charged to accumulated depreciation and if different than the assumptions under the depreciation study could potentially result in adjusted depreciation expense over a period of years. However, when removal costs exceed the salvage value on assets and the Company has no legal obligation to remove the assets, the removal costs incurred are charged to income in the period in which the assets are removed and are not charged to accumulated depreciation. For certain asset classes, the historical cost of the asset is separately recorded in the Company’s property records. This amount is retired from the property records upon retirement of the asset. For assets for which the historical cost cannot be separately identified the amount of the gross book value to be retired is estimated using either an indexation methodology, whereby the current replacement cost of the asset is indexed to the estimated year of installation for the asset, or a first-in, first-out approach, or statistical analysis is used to determine the age of the retired asset. CP uses indices that closely correlate to the principal costs of the assets. There are a number of estimates inherent in the depreciation and retirement processes and as it is not possible to precisely estimate each of these variables until a group of property is completely retired, CP regularly monitors the estimated service lives of assets and the associated accumulated depreciation for each asset class to ensure depreciation rates are appropriate. If the recorded amounts of accumulated depreciation are greater or less than the amounts indicated by the depreciation studies, then the excess or deficit is amortized as a component of depreciation expense over the remaining service lives of the applicable asset classes. For the sale or retirement of larger groups of depreciable assets that are unusual and were not considered in the Company’s depreciation studies, CP records a gain or loss for the difference between net proceeds and net book value of the assets sold or retired. The accumulated depreciation to be retired includes asset-specific accumulated depreciation, when known, and an appropriate portion of the accumulated depreciation recorded for the relevant asset class as a whole, calculated using a cost-based allocation. Revisions to the estimated useful lives and net salvage projections constitute a change in accounting estimate and are addressed prospectively by amending depreciation rates. Equipment under finance lease is included in Properties and depreciated over the period of expected use. Leases The Company has leases for rolling stock, buildings, vehicles, railway equipment, roadway machines, and information systems hardware. CP has entered into rolling stock and roadway machine leases that are fully variable or contain both fixed and variable components. Variable components are dependent on the hours and miles that the underlying equipment has been used. Fixed term, short-term, and variable operating lease costs are recorded in "Equipment rents" and "Purchased services and other" on the Company's Consolidated Statements of Income. Components of finance lease costs are recorded in "Depreciation and amortization" and "Net interest expense" on the Company's Consolidated Statements of Income. The Company determines lease existence and classification at the lease inception date. Leases are identified when an agreement conveys the right to control identified property for a period of time in exchange for consideration. The Company recognizes both an operating lease liability and right-of-use (“ROU”) asset for operating leases with fixed terms and in-substance fixed terms. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating and finance lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Lease payments include fixed and variable payments that are based on an index or a rate. If the Company's leases do not provide a readily determinable implicit interest rate, the Company uses internal incremental secured borrowing rates for comparable tenor in the same currency at the commencement date in determining the present value of lease payments. Operating and finance lease ROU assets also include lease prepayments and initial direct costs, but are reduced by lease incentives. The lease term may include periods associated with options to extend or exclude periods associated with options to terminate the lease when it is reasonably certain that the Company will exercise these options. The Company has short-term operating leases with terms of 12 months or less, some of which include options to purchase that the Company is not reasonably certain to exercise. The Company has elected to apply the recognition exemption and, as such, accounts for leases with a term of 12 months or less off-balance sheet. Therefore, lease payments on these short-term operating leases are not included in operating lease ROU assets and liabilities, but are recognized as an expense in the Company's Consolidated Statements of Income on a straight-line basis over the term of the lease. Further, the Company has elected to combine lease and non-lease components for all leases, except for leases of roadway machines and information systems hardware. Assets held for sale Assets to be disposed that meet the held for sale criteria are reported in "Other assets" at the lower of their carrying amount and fair value, less costs to sell, and are no longer depreciated. Goodwill and intangible assets Goodwill represents the excess of the purchase price over the fair value of identifiable net assets upon acquisition of a business. Goodwill is assigned to the reporting units that are expected to benefit from the business acquisition which, after integration of operations with the railway network, may be different than the acquired business. The carrying value of goodwill, which is not amortized, is assessed for impairment annually in the fourth quarter of each year as at October 1 st , or more frequently as economic events dictate. The Company has the option of performing an assessment of certain qualitative factors to determine if it is more likely than not that the fair value of a reporting unit is less than its carrying value or proceeding directly to a quantitative impairment test. Qualitative factors include but are not limited to, economic, market and industry conditions, cost factors and overall financial performance of the reporting unit. If the assessment of qualitative factors indicates that the carrying value is less than the fair value, then performing the quantitative goodwill impairment test is unnecessary. The quantitative assessment compares the fair value of the reporting unit to its carrying value, including goodwill. If the fair value of the reporting unit is less than its carrying value, goodwill is impaired. The impairment charge that would be recognized is the excess of the carrying value over the fair value of the reporting unit, limited to the total amount of goodwill allocated to the reporting unit. Intangible assets with finite lives are amortized on a straight-line basis over the estimated useful lives of the respective assets. Favourable leases, customer relationships and interline contracts have amortization periods ranging from 15 to 20 years. When there is a change in the estimated useful life of an intangible asset with a finite life, amortization is adjusted prospectively. Pensions and other benefits Pension costs are actuarially determined using the projected-benefit method pro-rated over the credited service periods of employees. This method incorporates management’s best estimates of expected plan investment performance, salary escalation and retirement ages of employees. The expected return on fund assets is calculated using market-related asset values developed from a five-year average of market values for the fund’s public equity securities and absolute return strategies (with each prior year’s market value adjusted to the current date for assumed investment income during the intervening period) plus the market value of the fund’s fixed income, real estate, infrastructure and private debt securities, subject to the market-related asset value not being greater than 120% of the market value nor being less than 80% of the market value. The discount rate used to determine the projected-benefit obligation is based on blended market interest rates on high-quality debt instruments with matching cash flows. Unrecognized actuarial gains and losses in excess of 10% of the greater of the benefit obligation and the market-related value of plan assets are amortized over the expected average remaining service period of active employees expected to receive benefits under the plan (approximately 12 years). Prior service costs arising from collectively bargained amendments to pension plan benefit provisions are amortized over the term of the applicable union agreement. Prior service costs arising from all other sources are amortized over the expected average remaining service period of active employees who are expected to receive benefits under the plan at the date of amendment. Costs for post-retirement and post-employment benefits other than pensions, including post-retirement health care and life insurance and some workers’ compensation and long-term disability benefits in Canada, are actuarially determined on a basis similar to pension costs. The over or under funded status of defined benefit pension and other post-retirement benefit plans are measured as the difference between the fair value of the plan assets and the benefit obligation, and are recognized on the balance sheets. In addition, any unrecognized actuarial gains and losses and prior service costs and credits that arise during the period are recognized as a component of “Other comprehensive loss”, net of tax. Gains and losses on post-employment benefits that do not vest or accumulate, including some workers’ compensation and long-term disability benefits in Canada, are included immediately on the Company's Consolidated Statements of Income as "Other components of net periodic benefit cost or recovery". The current service cost component of net periodic benefit cost is reported in "Compensation and benefits" for pensions and post-retirement benefits, and in "Purchased services and other" for self-insured workers' compensation and long-term disability benefits on the Company's Consolidated Statements of Income. Other components of net periodic benefit cost or recovery are reported in "Other components of net periodic benefit cost or recovery" outside of Operating income on the Company's Consolidated Statements of Income. Capitalization of pension costs, when applicable, is restricted to the current service cost component of net periodic benefit cost. Financial instruments Financial instruments are contracts that give rise to a financial asset of one party and a financial liability or equity instrument of another party. Financial instruments are recognized initially at fair value, which is the amount of consideration that would be agreed upon in an arm’s-length transaction between willing parties. Subsequent measurement depends on how the financial instruments have been classified. Accounts receivable and other investments, classified as loans and receivables, are measured at amortized cost, using the effective interest method. Cash and cash equivalents and derivatives are classified as held for trading and are measured at fair value. Accounts payable, accrued liabilities, short-term borrowings, other long-term liabilities, and long-term debt are also measured at amortized cost. Derivative financial instruments Derivative financial and commodity instruments may be used from time to time by the Company to manage its exposure to risks relating to foreign currency exchange rates, stock-based compensation, interest rates, and fuel prices. When CP utilizes derivative instruments in hedging relationships, CP identifies, designates, and documents those hedging transactions and regularly tests the transactions to demonstrate effectiveness in order to continue hedge accounting. All derivative instruments are classified as held for trading and recorded at fair value. Any change in the fair value of derivatives that are not designated as hedges is recognized in the period in which the change occurs in the Company's Consolidated Statements of Income in the line item to which the derivative instrument is related. For fair value hedges, the periodic changes in value are recognized in income, on the same line as the changes in value of the hedged items are also recorded. For an effective cash flow hedge, the entire change in value of the hedging instrument is recognized in “Other comprehensive loss”. The change in value of the effective cash flow hedge remains in “Accumulated other comprehensive loss” until the related hedged item settles, at which time amounts recognized in “Accumulated other comprehensive loss” are reclassified to the same income or balance sheet account that records the hedged item. Cash flows relating to derivative instruments designated as hedges are included in the same line as the related hedged items on the Company's Consolidated Statements of Cash Flows. Environmental remediation Environmental remediation accruals, recorded on an undiscounted basis unless a reliably determinable estimate as to amount and timing of costs can be established, cover site-specific remediation programs. The accruals are recorded when the costs to remediate are probable and reasonably estimable. Certain future costs to monitor sites are discounted at an adjusted risk-free rate. Provisions for environmental remediation costs are recorded in “Other long-term liabilities”, except for the current portion, which is recorded in “Accounts payable and accrued liabilities”. Stock-based compensation CP follows the fair value based approach to account for stock options. Compensation expense and an increase in “Additional paid-in capital” are recognized for stock options over their vesting period or over the period from the grant date to the date employees become eligible to retire, when this is shorter than the vesting period, based on their fair values on the grant date as determined using the Black-Scholes option-pricing model. Forfeitures are estimated at issuance and monitored on a periodic basis. Any consideration paid by employees on exercise of stock options is credited to “Share capital” when the option is exercised and the recorded fair value of the option is removed from “Additional paid-in capital" and credited to “Share capital”. Compensation expense is also recognized for performance share units (“PSUs”), performance deferred share units ("PDSUs"), deferred share units ("DSUs"), and restricted share units (“RSUs”) that settle in cash using the fair value method. Compensation expense is recognized over the vesting period or over the period from the grant date to the date employees become eligible to retire, when this is shorter than the vesting period where applicable. Forfeitures are estimated at issuance and monitored on a periodic basis. The employee share purchase plan gives rise to compensation expense that is recognized using the issue price by amortizing the cost over the vesting period.

Accounting Changes

Accounting Changes	12 Months Ended
	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Changes	Accounting changes Implemented in 2020 Financial Instruments - Credit Losses On January 1, 2020, the Company adopted the new Accounting Standards Update ("ASU") 2016-13, issued by the Financial Accounting Standards Board ("FASB"), and all related amendments under FASB Accounting Standards Codification ("ASC") Topic 326, Financial Instruments - Credit Losses. Using a modified retrospective approach, the Company recognized a cumulative-effect adjustment to its opening retained earnings balance in the period of adoption. Accordingly, comparative financial information has not been restated and continues to be reported under the accounting standards in effect for those periods. The impact of the adoption of ASC 326 as at January 1, 2020 was an increase in the allowance for credit losses of $1 million, with the offsets to "Deferred income taxes" and "Retained earnings" on the Company's Consolidated Balance Sheet. See Note 9 for further discussion of the current period credit loss. Simplification of Financial Disclosures about Guarantors During the second quarter of 2020, the Company early adopted the Securities and Exchange Commission amendments to the financial disclosure requirements for guarantors and issuers of guaranteed securities, as specified in Rule 3-10 of Regulation S-X. The amendments simplify disclosure requirements by replacing condensed consolidating financial information (“CCFI”) with summarized financial information and expanded qualitative non-financial disclosures about the guarantees, issuers, and guarantors. This disclosure can be found in Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations, Liquidity and Capital Resources.

Revenues

Revenues	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenues	Revenues The following table disaggregates the Company’s revenues from contracts with customers by major source: (in millions of Canadian dollars) 2020 2019 2018 Freight Grain $ 1,829 $ 1,684 $ 1,566 Coal 566 682 673 Potash 493 462 486 Fertilizers and sulphur 290 250 243 Forest products 328 304 284 Energy, chemicals and plastics 1,519 1,534 1,243 Metals, minerals and consumer products 629 752 797 Automotive 324 352 322 Intermodal 1,563 1,593 1,538 Total freight revenues 7,541 7,613 7,152 Non-freight excluding leasing revenues 107 116 102 Revenues from contracts with customers 7,648 7,729 7,254 Leasing revenues 62 63 62 Total revenues $ 7,710 $ 7,792 $ 7,316 Contract liabilities Contract liabilities represent payments received for performance obligations not yet satisfied and relate to deferred revenue and are presented as components of "Accounts payable and accrued liabilities" and "Other long-term liabilities" on the Company's Consolidated Balance Sheets. The following table summarizes the changes in contract liabilities for the years ended December 31, 2020 and 2019: (in millions of Canadian dollars) 2020 2019 Opening balance $ 146 $ 2 Revenue recognized that was included in the contract liability balance at the beginning of the period (100) (2) Increase due to consideration received, net of revenue recognized during the period 15 146 Closing balance $ 61 $ 146

Other Expense (Income)

Other Expense (Income)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other Income and Expenses	Other (income) expense (in millions of Canadian dollars) 2020 2019 2018 Foreign exchange (gain) loss on debt and lease liabilities $ (14) $ (94) $ 168 Other foreign exchange (gains) losses (1) (4) 3 Other 8 9 3 Other (income) expense $ (7) $ (89) $ 174

Net Interest Expense

Net Interest Expense	12 Months Ended
	Dec. 31, 2020
Interest Income (Expense), Net [Abstract]
Net Interest Expense	Net interest expense (in millions of Canadian dollars) 2020 2019 2018 Interest cost $ 478 $ 471 $ 475 Interest capitalized to Properties (16) (17) (20) Interest expense 462 454 455 Interest income (4) (6) (2) Net interest expense $ 458 $ 448 $ 453 Interest expense includes interest on finance leases of $11 million for the year ended December 31, 2020 (2019 – $11 million; 2018 – $11 million).

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income taxes The following is a summary of the major components of the Company’s income tax expense: (in millions of Canadian dollars) 2020 2019 2018 Current income tax expense $ 537 $ 525 $ 381 Deferred income tax expense Origination and reversal of temporary differences 277 316 214 Effect of tax rate decrease (32) (95) (21) Effect of hedge of net investment in foreign subsidiaries (18) (38) 64 Other (6) (2) (1) Total deferred income tax expense 221 181 256 Total income taxes $ 758 $ 706 $ 637 Income before income tax expense Canada $ 2,518 $ 2,392 $ 1,788 Foreign 684 754 800 Total income before income tax expense $ 3,202 $ 3,146 $ 2,588 Income tax expense Current Canada $ 412 $ 410 $ 336 Foreign 125 115 45 Total current income tax expense 537 525 381 Deferred Canada 231 141 174 Foreign (10) 40 82 Total deferred income tax expense 221 181 256 Total income taxes $ 758 $ 706 $ 637 The provision for deferred income taxes arises from temporary differences in the carrying values of assets and liabilities for financial statement and income tax purposes and the effect of loss carry forwards. The items comprising the deferred income tax assets and liabilities are as follows: (in millions of Canadian dollars) 2020 2019 Deferred income tax assets Amount related to tax losses carried forward $ 17 $ 6 Liabilities carrying value in excess of tax basis 131 139 Unrealized foreign exchange losses 4 26 Environmental remediation costs 22 22 Other 4 4 Total net deferred income tax assets 178 197 Deferred income tax liabilities Properties carrying value in excess of tax basis 3,708 3,524 Pensions carrying value in excess of tax basis 43 83 Other 93 91 Total deferred income tax liabilities 3,844 3,698 Total net deferred income tax liabilities $ 3,666 $ 3,501 The Company’s consolidated effective income tax rate differs from the expected Canadian statutory tax rates. Expected income tax expense at statutory rates is reconciled to income tax expense as follows: (in millions of Canadian dollars, except percentage) 2020 2019 2018 Statutory federal and provincial income tax rate (Canada) 26.31 % 26.77 % 26.86 % Expected income tax expense at Canadian enacted statutory tax rates $ 842 $ 842 $ 695 (Decrease) increase in taxes resulting from: (Gains) losses not subject to tax (23) (19) 8 Canadian tax rate differentials (3) — — Foreign tax rate differentials (32) (33) (55) Effect of tax rate decrease (32) (95) (21) Valuation allowance — (5) 5 Unrecognized tax benefits (7) 33 — Other 13 (17) 5 Income tax expense $ 758 $ 706 $ 637 In 2020, the Company revalued its deferred income tax balances as a result of a tax filing election for the state of North Dakota resulting in a lower corporate income tax rate and a net recovery of $29 million . In 2019, the Company revalued its deferred income tax balances as a result of a corporate income tax rate decrease in the province of Alberta, resulting in a net recovery of $88 million . In 2018, the Company revalued its deferred income tax balances as a result of corporate income tax rate decreases in the states of Iowa and Missouri, resulting in a net recovery of $21 million . The Company has not provided a deferred liability for the income taxes, if any, which might become payable on any temporary difference associated with its foreign investments because the Company intends to indefinitely reinvest in its foreign investments and has no intention to realize this difference by a sale of its interest in foreign investments. It is not practical to calculate the amount of the deferred tax liability. It is more likely than not that the Company will realize the majority of its deferred income tax assets from the generation of future taxable income, as the payments for provisions, reserves and accruals are made and losses and tax credits carried forward are utilized. At December 31, 2020, the Company had tax effected operating losses carried forward of $15 million (2019 – $4 million), which have been recognized as a deferred tax asset. The losses carried forward will begin to expire in 2031. The Company expects to fully utilize these tax effected operating losses before their expiry. The Company did not have any minimum tax credits or investment tax credits carried forward. At December 31, 2020, the Company had $2 million (2019 – $2 million) in tax effected capital losses carried forward recognized as a deferred tax asset. The Company has no unrecognized tax benefits from capital losses at December 31, 2020 and 2019. The following table provides a reconciliation of uncertain tax positions in relation to unrecognized tax benefits for Canada and the U.S. for the year ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Unrecognized tax benefits at January 1 $ 52 $ 13 $ 13 Increase in unrecognized: Tax benefits related to the current year — 9 1 Tax benefits related to prior years 10 34 — Dispositions: Gross uncertain tax benefits related to prior years (9) — (1) Settlements with taxing authorities 2 (4) — Unrecognized tax benefits at December 31 $ 55 $ 52 $ 13 If these uncertain tax positions were recognized, all of the amount of unrecognized tax positions as at December 31, 2020 would impact the Company’s effective tax rate. During the fourth quarter of 2019, a tax authority proposed an adjustment for a prior tax year without assessing taxes. Although the Company had commenced action to have the proposal removed, an increase in uncertain tax position was recorded on deferred income tax liability and expense in the amount of $24 million. While the proposed adjustment was withdrawn during 2020, the ultimate resolution of this matter may give rise to further favourable or unfavourable adjustments to deferred tax, the timing and amount of which are not determinable at this time. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as a component of "Income tax expense" in the Company’s Consolidated Statements of Income. The net amount of accrued interest and penalties in 2020 was a $1 million recovery (2019 – $1 million recovery; 2018 – $nil). The total amount of accrued interest and penalties associated with unrecognized tax benefits at December 31, 2020 was $9 million (2019 – $10 million; 2018 – $11 million). The Company and its subsidiaries are subject to either Canadian federal and provincial income tax, U.S. federal, state and local income tax, or the relevant income tax in other international jurisdictions. The Company has substantially concluded all Canadian federal and provincial income tax matters for the years through 2014. The federal and provincial income tax returns filed for 2015 and subsequent years remain subject to examination by the Canadian taxation authorities. The Internal Revenue Service ("IRS") audit for 2012 and 2013 has been settled. The income tax returns for 2016 and subsequent years continue to remain subject to examination by the IRS and U.S. state tax jurisdictions. The Company believes that it has recorded sufficient income tax reserves at December 31, 2020 with respect to these income tax examinations.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per share Basic earnings per share has been calculated using Net income for the year divided by the weighted-average number of shares outstanding during the year. Diluted earnings per share has been calculated using the treasury stock method which assumes that any proceeds received from the exercise of in-the-money options would be used to purchase CP Common Shares at the average market price for the period. For purposes of this calculation, at December 31, 2020, there were 1.4 million dilutive options outstanding (2019 – 1.6 million; 2018 – 1.3 million). The number of shares used in the earnings per share calculations are reconciled as follows: (in millions of Canadian dollars, except per share data) 2020 2019 2018 Net income $ 2,444 $ 2,440 $ 1,951 Weighted-average basic shares outstanding (millions) 135.5 138.8 142.9 Dilutive effect of stock options (millions) 0.5 0.5 0.4 Weighted-average diluted shares outstanding (millions) 136.0 139.3 143.3 Earnings per share – basic $ 18.05 $ 17.58 $ 13.65 Earnings per share – diluted $ 17.97 $ 17.52 $ 13.61 In 2020, there were no options excluded from the computation of diluted earnings per share (2019 – nil; 2018 – 0.2 million).

Other Comprehensive Income (Los

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2020
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss	Other comprehensive loss and accumulated other comprehensive loss The components of Other comprehensive loss and the related tax effects are as follows: (in millions of Canadian dollars) Before Income tax (expense) recovery Net of tax For the year ended December 31, 2020 Unrealized foreign exchange (loss) gain on: Translation of the net investment in U.S. subsidiaries $ (118) $ — $ (118) Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) 136 (18) 118 Realized loss on derivatives designated as cash flow hedges recognized in income 9 (3) 6 Change in pension and other benefits actuarial gains and losses (403) 108 (295) Change in prior service pension and other benefit costs (4) 1 (3) Other comprehensive loss $ (380) $ 88 $ (292) For the year ended December 31, 2019 Unrealized foreign exchange (loss) gain on: Translation of the net investment in U.S. subsidiaries $ (251) $ — $ (251) Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) 288 (38) 250 Realized loss on derivatives designated as cash flow hedges recognized in income 10 (2) 8 Change in pension and other benefits actuarial gains and losses (661) 175 (486) Other comprehensive loss $ (614) $ 135 $ (479) For the year ended December 31, 2018 Unrealized foreign exchange gain (loss) on: Translation of the net investment in U.S. subsidiaries $ 419 $ — $ 419 Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) (479) 64 (415) Change in derivatives designated as cash flow hedges: Realized loss on cash flow hedges recognized in income 10 (3) 7 Unrealized gain on cash flow hedges and other 28 (8) 20 Change in pension and other benefits actuarial gains and losses (447) 115 (332) Change in prior service pension and other benefit costs (2) 1 (1) Other comprehensive loss $ (471) $ 169 $ (302) The components of Accumulated other comprehensive loss, net of tax, are as follows: (in millions of Canadian dollars) 2020 2019 Unrealized foreign exchange gain on translation of the net investment in U.S. subsidiaries $ 493 $ 611 Unrealized foreign exchange loss on translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (381) (499) Net deferred losses on derivatives and other (48) (54) Amounts for defined benefit pension and other post-retirement plans not recognized in income (Note 22) (2,878) (2,580) Accumulated other comprehensive loss $ (2,814) $ (2,522) Changes in Accumulated other comprehensive loss by component are as follows: (in millions of Canadian dollars) Foreign currency (1) Derivatives and (1) Pension and post- (1) Total (1) Opening balance, January 1, 2020 $ 112 $ (54) $ (2,580) $ (2,522) Other comprehensive loss before reclassifications — (2) (430) (432) Amounts reclassified from accumulated other comprehensive loss — 8 132 140 Net other comprehensive income (loss) — 6 (298) (292) Closing balance, December 31, 2020 $ 112 $ (48) $ (2,878) $ (2,814) Opening balance, January 1, 2019 $ 113 $ (62) $ (2,094) $ (2,043) Other comprehensive loss before reclassifications (1) — (550) (551) Amounts reclassified from accumulated other comprehensive loss — 8 64 72 Net other comprehensive (loss) income (1) 8 (486) (479) Closing balance, December 31, 2019 $ 112 $ (54) $ (2,580) $ (2,522) (1) Amounts are presented net of tax. Amounts in Pension and post-retirement defined benefit plans reclassified from Accumulated other comprehensive loss are as follows: (in millions of Canadian dollars) 2020 2019 Amortization of prior service costs (1) $ (1) $ — Recognition of net actuarial loss (1) 180 84 Total before income tax 179 84 Income tax recovery (47) (20) Total net of income tax $ 132 $ 64 (1) Impacts "Other components of net periodic benefit recovery" on the Consolidated Statements of Income.

Accounts Receivable, Net

Accounts Receivable, Net	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Accounts and Nontrade Receivable	Accounts receivable, net As at December 31, 2020 As at December 31, 2019 (1) (in millions of Canadian dollars) Freight Non-Freight Total Freight Non-Freight Total Total accounts receivable $ 662 $ 203 $ 865 $ 637 $ 210 $ 847 Allowance for credit losses (25) (15) (40) (26) (16) (42) Total accounts receivable, net $ 637 $ 188 $ 825 $ 611 $ 194 $ 805 (1) Prior year amounts have not been adjusted under the modified retrospective method (Note 2). For the twelve months ended December 31, 2020 (in millions of Canadian dollars) Freight Non-Freight Total Allowance for credit losses, opening balance (1) $ (27) $ (16) $ (43) Current period credit loss provision, net 2 1 3 Allowance for credit losses, closing balance $ (25) $ (15) $ (40) (1) Opening balance at January 1, 2020 was restated as described in Note 2.

Business combination (Notes)

Business combination (Notes)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Business combination	Business combinations DRTP On December 22, 2020, CP completed its acquisition of the 83.5% ownership of the Detroit River Tunnel Partnership (“DRTP”) held by OMERS Infrastructure Management Inc. (“OMERS”) for cash, net of cash acquired, of $398 million. The purchase price is subject to customary closing adjustments, including any final adjustment for closing working capital and certain closing costs. With this acquisition CP obtained 100% ownership of DRTP. The acquisition of DRTP will reduce CP’s operating costs related to movements through the tunnel which amounted to approximately $34 million in 2020, and better integrate the eastern part of the network. DRTP owns a 1.6-mile rail tunnel linking Windsor, Ontario, and Detroit, Michigan and additional, separate lands in both cities. The acquisition was funded with cash from operations and CP's commercial paper program. The acquisition of DRTP has been accounted for as a business combination under the acquisition method of accounting. The acquired assets and assumed liabilities are recorded at their estimated fair values at the date of acquisition. The fair values were estimated by applying an income approach using the discounted cash flow method of future cash flows, appraised land values reflecting a corridor enhancement factor where appropriate, and depreciated replacement cost for depreciable assets including the tunnel, track, signaling systems, and other railway related infrastructure assets. Prior to the close of the transaction, CP owned a 16.5% interest in DRTP, which was accounted for as an equity method investment. The previously held equity investment was remeasured to fair value which was determined from the negotiated purchase price that reflected a market value established in a competitive bid process. As a result of the acquisition, the Company recognized a before-tax gain of $68 million on the remeasurement to fair value of its equity interest within "Purchased services and other", calculated as the difference between the fair value of CP's 16.5% interest in DRTP of $81 million and the book value of the interest of $13 million. The purchase price allocation was prepared on a preliminary basis and is subject to change as additional information becomes available concerning the fair value and tax bases of the net assets acquired. Any adjustments to the purchase price allocation will be made as soon as practicable but no later than one year from the date of acquisition. The following summarizes the estimated fair values of the acquired assets and liabilities of DRTP: (in millions of Canadian dollars) December 22, 2020 Fair value of net assets acquired: Accounts receivable, net $ 5 Properties 436 Intangible assets (Note 13) 4 Accounts payable and accrued liabilities (1) Deferred taxes (55) Total identifiable assets and liabilities $ 389 Goodwill (Note 13) 90 $ 479 Consideration: Cash, net of cash acquired $ 398 Fair value of previously held equity method investment 81 Total consideration $ 479 The goodwill of $90 million relates primarily to the contract that DRTP has for CP’s use of the tunnel and deferred taxes recognized as a result of the purchase price allocation. The goodwill recognized is not deductible for tax purposes. Prior to the acquisition of DRTP, CP had pre-existing agreements to use the tunnel and to operate and manage the tunnel on behalf of DRTP. On acquisition, no gain or loss was recognized in respect of the effective settlement of these pre-existing relationships as they were determined to be at fair market value based on an assessment of current market conditions and market participants. Acquired cash and cash equivalents of $6 million is presented as a reduction of cash used in investing activities in the Company's Consolidated Statements of Cash Flows. CP has not provided pro forma information relating to the pre-acquisition period as it is not material. CMQ On December 30, 2019, CP purchased 100% of Central Maine & Québec Railway Canada Inc. (“CMQ Canada”) and Central Maine & Québec Railway U.S. Inc. (“CMQ U.S.”) (together “CMQ”) for cash consideration of $174 million. CMQ owns 237 miles of rail lines in Québec and 244 miles of rail lines in Maine and Vermont. CMQ U.S. The acquisition of CMQ U.S. was subject to approval from the United States Surface Transportation Board ("STB"). From the December 30, 2019 date of purchase, all purchased shares of CMQ U.S. were held in an independent voting trust (the "Trust") pending the STB's approval of CP's application for control of CMQ U.S. Approval was granted with an effective date of June 3, 2020. Between December 30, 2019 and June 3, 2020, CP accounted for its acquisition of CMQ U.S. as an equity method investment. During this time, CP paid additional consideration for CMQ of $3 million, representing changes from the finalization of previously estimated closing date working capital. On June 3, 2020 the Trust was dissolved and CP assumed control of CMQ U.S. At this time, CP accounted for its acquisition in CMQ U.S. as a business combination using the acquisition method of accounting. Accordingly, the acquired tangible and intangible assets and assumed liabilities were recorded at their estimated fair values as at June 3, 2020 and results from operations and cash flows were consolidated prospectively. There was no material change in the acquisition-date fair value of the equity interest held by the Company in CMQ U.S. immediately before the acquisition date. Fair values were determined primarily through the use of an income approach. After a measurement period adjustment of $1 million to increase Other long-term liabilities and goodwill resulting from the finalization of acquisition date deferred tax, the final allocation of total consideration to the fair values of the acquired assets and liabilities of CMQ U.S. is summarized as follows: (in millions of Canadian dollars) June 3, 2020 Fair value of net assets acquired: Cash and cash equivalents $ 22 Accounts receivable, net 2 Properties 54 Intangible assets (Note 13) 27 Accounts payable and accrued liabilities (13) Other long-term liabilities (6) Total identifiable assets and liabilities $ 86 Goodwill (Note 13) 52 $ 138 Consideration: Fair value of previously held equity method investment $ 138 Goodwill of $52 million relates primarily to expected operating business synergies between the Company and CMQ U.S. The factors that contribute to the goodwill are revenue growth from customers which are currently not served by CP, access to new routes, and an assembled workforce. Goodwill recognized is not deductible for tax purposes. Intangible assets of $27 million reflect customer lists acquired in the purchase of CMQ U.S., and have amortization periods of 20 years. Acquired cash and cash equivalents of $22 million is presented as a reduction of cash used in investing activities on the Company's Consolidated Statement of Cash Flows, and is presented net of finalized closing working capital adjustments for CMQ of $3 million as described above. CP has not provided pro forma information relating to the pre-acquisition period as it is not material. CMQ Canada The acquisition of CMQ Canada was accounted for as a business combination under the acquisition method of accounting. The acquired tangible and intangible assets and assumed liabilities are recorded at their estimated fair values at the date of acquisition. There have been no adjustments to the preliminary purchase price allocation. The final purchase price and allocation of the total consideration to the fair values of assets and liabilities acquired for CMQ Canada is summarized as follows: (in millions of Canadian dollars) December 30, 2019 Fair value of net assets acquired: Accounts receivable, net $ 7 Properties 42 Intangible assets (Note 13) 5 Accounts payable and accrued liabilities (2) Long-term debt maturing within one year (Note 16) (11) Other long-term liabilities (4) Total identifiable assets and liabilities 37 Goodwill (Note 13) 10 $ 47 Consideration: Cash, net of cash acquired $ 47 The goodwill of $10 million relates primarily to expected operating business synergies. The factors that contribute to the goodwill are revenue growth from customers which are currently not served by CP, access to new routes and an assembled workforce. The goodwill recognized is not deductible for tax purposes. CP has not provided pro forma information relating to the pre-acquisition period as it is not material.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investments	Investments (in millions of Canadian dollars) 2020 2019 Investment in CMQ U.S. accounted for on an equity basis (Note 10) $ — $ 127 Other rail investments accounted for on an equity basis 150 166 Other investments 49 48 Total investments $ 199 $ 341

Properties

Properties	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Properties	Properties 2020 2020 2019 (in millions of Canadian dollars except percentages) Weighted-average annual depreciation rate Cost Accumulated Net book Cost Accumulated Net book Track and roadway 2.8 % $ 20,676 $ 5,859 $ 14,817 $ 19,299 $ 5,522 $ 13,777 Buildings 2.9 % 937 259 678 833 237 596 Rolling stock 2.8 % 4,702 1,498 3,204 4,529 1,445 3,084 Information systems software (1) 9.3 % 569 253 316 527 215 312 Other 5.2 % 2,167 760 1,407 2,067 680 1,387 Total $ 29,051 $ 8,629 $ 20,422 $ 27,255 $ 8,099 $ 19,156 (1) During 2020, CP capitalized costs attributable to the design and development of internal-use software in the amount of $45 million (2019 – $55 million; 2018 – $53 million). Current year depreciation expense related to internal use software was $42 million (2019 – $44 million; 2018 – $49 million). Finance leases included in properties 2020 2019 (in millions of Canadian dollars) Cost Accumulated Net book Cost Accumulated Net book Rolling stock 302 138 164 303 130 173 Other 8 1 7 4 — 4 Total assets held under finance lease $ 310 $ 139 $ 171 $ 307 $ 130 $ 177

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and intangible assets Goodwill Intangible assets (in millions of Canadian dollars) Net Cost Accumulated Net Total goodwill and intangible assets Balance at December 31, 2018 $ 194 $ 22 $ (14) $ 8 $ 202 Additions (Note 10) 10 5 — 5 15 Amortization — — (1) (1) (1) Foreign exchange impact (10) — — — (10) Balance at December 31, 2019 194 27 (15) 12 206 Additions (Note 10) 142 31 — 31 173 Amortization — — (3) (3) (3) Foreign exchange impact (7) (3) — (3) (10) Balance at December 31, 2020 $ 329 $ 55 $ (18) $ 37 $ 366

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Other assets (in millions of Canadian dollars) 2020 2019 Operating lease ROU assets (Note 19) $ 316 $ 358 Contracted customer incentives 60 32 Long-term materials 37 41 Other 25 20 Total other assets $ 438 $ 451

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities (in millions of Canadian dollars) 2020 2019 Trade payables $ 401 $ 453 Accrued charges 294 348 Accrued interest 134 131 Dividends payable 127 114 Stock-based compensation liabilities 121 85 Income and other taxes payable 115 139 Payroll-related accruals 68 78 Operating lease liabilities (Note 19) 63 69 Accrued vacation 59 60 Personal injury and other claims provision 37 55 Deferred revenue (Note 3) 27 142 Deferred real estate lease and license revenue (1) 11 10 Provision for environmental remediation (Note 18) 9 7 Other (1) 1 2 Total accounts payable and accrued liabilities $ 1,467 $ 1,693

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	Debt Long-term debt includes debt instruments and finance lease obligations. The following table outlines the Company's outstanding long-term debt as at December 31, 2020: (in millions of Canadian dollars except percentages) Maturity Currency 2020 2019 9.450% 30-year Debentures (A) Aug 2021 U.S.$ 318 325 5.100% 10-year Medium Term Notes (A) Jan 2022 CDN$ 125 125 4.500% 10-year Notes (A) Jan 2022 U.S.$ 318 324 4.450% 12.5-year Notes (A) Mar 2023 U.S.$ 445 454 2.900% 10-year Notes (A) Feb 2025 U.S.$ 891 909 3.700% 10.5-year Notes (A) Feb 2026 U.S.$ 318 324 4.000% 10-year Notes (A) Jun 2028 U.S.$ 636 649 3.150% 10-year Notes (A) Mar 2029 CDN$ 399 399 2.050% 10-year Notes (A) Mar 2030 U.S.$ 636 — 7.125% 30-year Debentures (A) Oct 2031 U.S.$ 446 454 5.750% 30-year Debentures (A) Mar 2033 U.S.$ 312 318 4.800% 20-year Notes (A) Sep 2035 U.S.$ 381 388 5.950% 30-year Notes (A) May 2037 U.S.$ 567 578 6.450% 30-year Notes (A) Nov 2039 CDN$ 400 400 5.750% 30-year Notes (A) Jan 2042 U.S.$ 313 319 4.800% 30-year Notes (A) Aug 2045 U.S.$ 698 712 3.050% 30-year Notes (A) Mar 2050 CDN$ 298 — 6.125% 100-year Notes (A) Sep 2115 U.S.$ 1,146 1,169 8.000% 5-year Promissory Notes (B) up to Jun 2020 U.S.$ — 11 5.41% Senior Secured Notes (C) Mar 2024 U.S.$ 89 100 6.91% Secured Equipment Notes (D) Oct 2024 CDN$ 75 91 7.49% Equipment Trust Certificates (E) Jan 2021 U.S.$ 14 55 Obligations under finance leases 1.99% -2.97% (F) 2021 - 2023 CDN$/U.S.$ 4 3 6.99% (F) Mar 2022 U.S.$ 97 99 6.57% (F) Dec 2026 U.S.$ 38 45 12.77% (F) Jan 2031 CDN$ 4 4 Commercial Paper up to Feb 2021 U.S.$ 820 516 9,788 8,771 Perpetual 4% Consolidated Debenture Stock (G) U.S.$ 39 39 Perpetual 4% Consolidated Debenture Stock (G) G.B.£ 6 6 9,833 8,816 Unamortized fees on long-term debt (62) (59) 9,771 8,757 Less: Long-term debt maturing within one year 1,186 599 $ 8,585 $ 8,158 At December 31, 2020, the gross amount of long-term debt denominated in U.S. dollars was U.S. $6,713 million (2019 – U.S. $6,016 million). Annual maturities and principal repayment requirements, excluding those pertaining to finance leases, for each of the five years following 2020 are (in millions): 2021 – $1,178 ; 2022 – $471; 2023 – $475; 2024 – $83; 2025 – $891 . Fees on long-term debt are amortized to income over the term of the related debt. A. These debentures and notes are presented net of unamortized discounts, pay interest semi-annually, and are unsecured but carry a negative pledge. In 2020, the Company issued U.S $500 million 2.050% 10-year Notes due March 5, 2030 for net proceeds of U.S. $495 million ($662 million) and $300 million 3.050% 30-year Notes due March 9, 2050 for net proceeds of $296 million. In 2019, the Company repaid U.S. $350 million 7.250% 10-year Notes at maturity for a total of U.S. $350 million ($471 million). The Company also issued $400 million 3.150% 10-year Notes due March 13, 2029 for net proceeds of $397 million. B. On December 30, 2019, through its business combination with CMQ Canada, the Company assumed CMQ Canada's obligations under the 8.00% 5-year Promissory Notes totalling U.S. $8 million ($11 million) owing to CMQ U.S (see Note 10). In 2020, these notes were settled. C. The 5.41% Senior Secured Notes are collateralized by specific locomotive units with a carrying value of $97 million at December 31, 2020. The Company pays equal blended semi-annual payments of principal and interest. Final repayment of the remaining principal of U.S. $44 million is due in March 2024. D. The 6.91% Secured Equipment Notes are full recourse obligations of the Company collateralized by a first charge on specific locomotive units with a carrying value of $54 million at December 31, 2020. The Company pays equal blended semi-annual payments of principal and interest. Final repayment of the remaining principal of $11 million is due in October 2024. E. The 7.49% Equipment Trust Certificates are secured by specific locomotive units with a carrying value of $91 million at December 31, 2020. The Company makes semi-annual payments that vary in amount and are interest-only payments or blended principal and interest payments. Final repayment of the remaining principal of U.S. $11 million is due in January 2021. F. The carrying value of the assets collateralizing finance lease obligations was $171 million at December 31, 2020. G. The Consolidated Debenture Stock, authorized by an Act of Parliament of 1889 , constitutes a first charge upon and over the whole of the undertaking, railways, works, rolling stock, plant, property and effects of the Company, with certain exceptions. Credit facility CP has a revolving credit facility (the “facility”) agreement with 14 highly rated financial institutions for a commitment amount of U.S. $1.3 billion, which consists of a U.S. $1.0 billion tranche maturing September 27, 2024 and a U.S. $300 million tranche maturing September 27, 2021. The facility can accommodate draws of cash and/or letters of credit at market competitive pricing. The agreement requires the Company to maintain a financial covenant in conjunction with the facility. As at December 31, 2020 and 2019, the Company was in compliance with all terms and conditions of the credit facility arrangements and satisfied the financial covenant. During the year ended December 31, 2020, the Company drew and fully repaid U.S. $100 million from the U.S. $300 million tranche of its revolving credit facility. As at December 31, 2020 and 2019, the facility was undrawn. The Company also has a commercial paper program which enables it to issue commercial paper up to a maximum aggregate principal amount of U.S . $1.0 billion in the form of unsecured promissory notes. This commercial paper program is backed by the revolving credit facility. As at December 31, 2020, the Company had total commercial paper borrowings of U.S. $644 million ( $820 million ), included in "Long-term debt maturing within one year" on the Company's Consolidated Balance Sheets (December 31, 2019 – $516 million). The weighted-average interest rate on these borrowings was 0.27% (December 31, 2019 - 2.03%) . The Company presents issuances and repayments of commercial paper, all of which have a maturity of less than 90 days, in the Company's Consolidated Statements of Cash Flows on a net basis. C P has bilateral letter of credit facilities with six highly rated financial institutions to support its requirement to post letters of credit in the ordinary course of business. Under these agreements, the Company has the option to post collateral in the form of cash or cash equivalents, equal at least to the face value of the letter of credit issued. These agreements permit CP to withdraw amounts posted as collateral at any time; therefore, the amounts posted as collateral are presented as “Cash and cash equivalents” on the Company’s Consolidated Balance Sheets. As at December 31, 2020 and 2019, the Company did not have any collateral posted on its bilateral letter of credit facilities but had letters of credit drawn of $59 million (December 31, 2019 – $80 million) from a total available amount of $300 million (December 31, 2019 – $300 million).

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial instruments A. Fair values of financial instruments The Company categorizes its financial assets and liabilities measured at fair value into a three-level hierarchy established by GAAP that prioritizes those inputs to valuation techniques used to measure fair value based on the degree to which they are observable. The three levels of the fair value hierarchy are as follows: Level 1 inputs are quoted prices in active markets for identical assets and liabilities; Level 2 inputs, other than quoted prices included within Level 1, are observable for the asset or liability either directly or indirectly; and Level 3 inputs are not observable in the market. The Company’s short-term financial instruments include cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and short-term borrowings including commercial paper. The carrying value of short-term financial instruments approximate their fair values. The carrying value of the Company’s long-term debt does not approximate its fair value. The estimated fair value has been determined based on market information where available, or by discounting future payments of principal and interest at estimated interest rates expected to be available to the Company at period end. All measurements are classified as Level 2. The Company’s long-term debt, including current maturities, with a carrying value of $8,951 million at December 31, 2020 (December 31, 2019 - $8,241 million), had a fair value of $11,597 million (December 31, 2019 - $10,149 million). B. Financial risk management Derivative financial instruments Derivative financial instruments may be used to selectively reduce volatility associated with fluctuations in interest rates, FX rates, the price of fuel, and stock-based compensation expense. Where derivatives are designated as hedging instruments, the relationship between the hedging instruments and their associated hedged items is documented, as well as the risk management objective and strategy for the use of the hedging instruments. This documentation includes linking the derivatives that are designated as fair value or cash flow hedges to specific assets or liabilities on the Company's Consolidated Balance Sheets, commitments, or forecasted transactions. At the time a derivative contract is entered into and at least quarterly thereafter, an assessment is made as to whether the derivative item is effective in offsetting the changes in fair value or cash flows of the hedged items. The derivative qualifies for hedge accounting treatment if it is effective in substantially mitigating the risk it was designed to address. It is not the Company’s intent to use financial derivatives or commodity instruments for trading or speculative purposes. Credit risk management Credit risk refers to the possibility that a customer or counterparty will fail to fulfill its obligations under a contract and as a result create a financial loss for the Company. The railway industry predominantly serves financially established customers, and the Company has experienced limited financial losses with respect to credit risk. The credit worthiness of customers is assessed using credit scores supplied by a third party and through direct monitoring of their financial well-being on a continual basis. The Company establishes guidelines for customer credit limits and should thresholds in these areas be reached, appropriate precautions are taken to improve collectability. Counterparties to financial instruments expose the Company to credit losses in the event of non-performance. Counterparties for derivative and cash transactions are limited to high credit quality financial institutions, which are monitored on an ongoing basis. Counterparty credit assessments are based on the financial health of the institutions and their credit ratings from external agencies. The Company does not anticipate non-performance that would materially impact the Company’s financial statements. In addition, the Company believes there are no significant concentrations of credit risk. FX management The Company conducts business transactions and owns assets in both Canada and the United States. As a result, the Company is exposed to fluctuations in the value of financial commitments, assets, liabilities, income, or cash flows due to changes in FX rates. The Company may enter into FX risk management transactions primarily to manage fluctuations in the exchange rate between Canadian and U.S. currencies. FX exposure is primarily mitigated through natural offsets created by revenues, expenditures, and balance sheet positions incurred in the same currency. Where appropriate, the Company may negotiate with customers and suppliers to reduce the net exposure. Net investment hedge The FX gains and losses on long-term debt are mainly unrealized and can only be realized when U.S. dollar-denominated long-term debt matures or is settled. The Company also has long-term FX exposure on its investment in foreign subsidiaries with a U.S. dollar functional currency. The majority of the Company’s U.S. dollar-denominated long-term debt has been designated as a hedge of the net investment in these foreign subsidiaries. This designation has the effect of mitigating volatility on Net income by offsetting long-term FX gains and losses on U.S. dollar-denominated long-term debt and gains and losses on its net investment. The effect of the net investment hedge recognized in “Other comprehensive loss” in 2020 was an FX gain of $136 million , the majority of which was unrealized (2019 – unrealized gain of $288 million; 2018 – unrealized loss of $479 million ) (see Note 8). Interest rate management The Company is exposed to interest rate risk, which is the risk that the fair value or future cash flows of a financial instrument will vary as a result of changes in market interest rates. In order to manage funding needs or capital structure goals, the Company enters into debt or finance lease agreements that are subject to either fixed market interest rates set at the time of issue or floating rates determined by ongoing market conditions. Debt subject to variable interest rates exposes the Company to variability in interest expense, while debt subject to fixed interest rates exposes the Company to variability in the fair value of debt. To manage interest rate exposure, the Company accesses diverse sources of financing and manages borrowings in line with a targeted range of capital structure, debt ratings, liquidity needs, maturity schedule, and currency and interest rate profiles. In anticipation of future debt issuances, the Company may enter into forward rate agreements, that are designated as cash flow hedges, to substantially lock in all or a portion of the effective future interest expense. The Company may also enter into swap agreements, designated as fair value hedges, to manage the mix of fixed and floating rate debt. Forward starting swaps During the second quarter of 2018, the Company settled a notional amount of U.S. $500 million of forward starting swaps related to the U.S. $500 million 4.000% 10-year Notes issued in the same period. The fair value of these derivative instruments at the time of settlement was a loss of U.S. $19 million ($24 million). The Company no longer has any active forward starting swaps. For the year ended December 31, 2020, a net loss of $9 million related to previously settled forward starting swap hedges has been amortized to “Net interest expense” (2019 – loss of $9 million; 2018 – loss of $10 million). The Company expects that during the next 12 months, $9 million of net losses will be amortized to “Net interest expense”. Treasury rate locks At December 31, 2020, the Company had net unamortized losses related to interest rate locks, which are accounted for as cash flow hedges, settled in previous years totalling $17 million (December 31, 2019 – $18 million). This amount is composed of various unamortized gains and losses related to specific debts which are reflected in “Accumulated other comprehensive loss” and are amortized to “Net interest expense” in the period that interest on the related debt is charged. The amortization of these gains and losses resulted in a $1 million increase to “Net interest expense” and “Other comprehensive loss” in 2020 (2019 – $1 million; 2018 – $1 million). The Company expects that during the next 12 months, a net loss of $1 million related to these previously settled derivatives will be reclassified to “Net interest expense”.

Other Long-Term Liabilities

Other Long-Term Liabilities	12 Months Ended
	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	Other long-term liabilities (in millions of Canadian dollars) 2020 2019 Operating lease liabilities, net of current portion (Note 19) $ 248 $ 285 Stock-based compensation liabilities, net of current portion 146 111 Provision for environmental remediation, net of current portion (1) 71 70 Deferred revenue, net of current portion (Note 3) (2) 34 4 Deferred real estate lease and license revenue, net of current portion (3) 18 20 Deferred gains on sale leaseback transactions (3) 5 6 Other, net of current portion (2) 63 66 Total other long-term liabilities $ 585 $ 562 (1) As at December 31, 2020, the aggregate provision for environmental remediation, including the current portion was $80 million (2019 – $77 million). (2) 2019 comparative figures have been reclassified to conform with current presentation. (3) The deferred real estate lease and license revenue and deferred gains on sale leaseback transactions are being amortized to income on a straight-line basis over the related lease terms. Environmental remediation accruals Environmental remediation accruals cover site-specific remediation programs. The estimate of the probable costs to be incurred in the remediation of properties contaminated by past railway activities reflects the nature of contamination at individual sites according to typical activities and scale of operations conducted. CP has developed remediation strategies for each property based on the nature and extent of the contamination, as well as the location of the property and surrounding areas that may be adversely affected by the presence of contaminants, considering available technologies, treatment and disposal facilities and the acceptability of site-specific plans based on the local regulatory environment. Site-specific plans range from containment and risk management of the contaminants through to the removal and treatment of the contaminants and affected soils and groundwater. The details of the estimates reflect the environmental liability at each property. Provisions for environmental remediation costs are recorded in “Other long-term liabilities”, except for the current portion which is recorded in “Accounts payable and accrued liabilities” (see Note 15). Payments are expected to be made over 10 years to 2030.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Leases The Company’s leases have remaining terms of less than one year to 14 years, some include options to extend up to an additional 10 years, and some include options to terminate within one year. Residual value guarantees are provided on certain vehicle operating leases. Cumulatively, these guarantees are limited to $1 million and are not included in lease liabilities as it is not currently probable that any amounts will be owed. Components of lease expense for the year ended December 31 are as follows: (in millions of Canadian dollars) 2020 2019 Operating lease cost $ 83 $ 89 Short-term lease cost 10 10 Variable lease cost 13 13 Sublease income (3) (3) Finance Lease Cost Amortization of right-of-use assets 9 9 Interest on lease liabilities 11 11 Total lease costs $ 123 $ 129 Supplemental balance sheet information related to leases is as follows: (in millions of Canadian dollars) Classification 2020 2019 Assets Operating Other assets $ 316 $ 358 Finance Properties, net book value 171 177 Liabilities Current Operating Accounts payable and accrued liabilities 63 69 Finance Long-term debt maturing within one year 8 7 Long-term Operating Other long-term liabilities 248 285 Finance Long-term debt 135 144 The following table provides the Company's weighted-average remaining lease terms and discount rates: 2020 2019 Weighted-Average Remaining Lease Term Operating leases 7 years 7 years Finance leases 3 years 4 years Weighted-Average Discount Rate Operating leases 3.32 % 3.45 % Finance leases 7.06 % 7.07 % Supplemental information related to leases is as follows: (in millions of Canadian dollars) 2020 2019 Cash paid for amounts included in measurement of lease liabilities Operating cash outflows from operating leases $ 74 $ 82 Operating cash outflows from finance leases 10 10 Financing cash outflows from finance leases 8 6 Right-of-use assets obtained in exchange for lease liabilities Operating leases 34 38 Finance leases 4 4 The following table provides the maturities of lease liabilities for the next five years and thereafter as at December 31, 2020: (in millions of Canadian dollars) Finance Leases Operating Leases 2021 $ 11 $ 71 2022 107 59 2023 9 53 2024 8 42 2025 8 34 Thereafter 12 88 Total lease payments 155 347 Imputed interest (12) (36) Present value of lease payments $ 143 $ 311

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Shareholders' Equity	Shareholders’ equity Authorized and issued share capital The Company is authorized to issue an unlimited number of Common Shares, an unlimited number of First Preferred Shares, and an unlimited number of Second Preferred Shares. At December 31, 2020, no First or Second Preferred Shares had been issued. The following table summarizes information related to Common Share balances as at December 31: (number of shares in millions) 2020 2019 2018 Share capital, January 1 137.0 140.5 144.9 CP Common Shares repurchased (4.0) (3.8) (4.6) Shares issued under stock option plan 0.3 0.3 0.2 Share capital, December 31 133.3 137.0 140.5 The change in the “Share capital” balance includes $10 million of stock-based compensation transferred from “Additional paid-in capital” (2019 – $7 million; 2018 – $12 million). Share repurchases On December 17, 2019, the Company announced a normal course issuer bid ("NCIB"), commencing December 20, 2019, to purchase up to 4.80 million Common Shares in the open market for cancellation on or before December 19, 2020. Upon expiry of this NCIB, the Company had purchased 4.27 million Common Shares for $1,577 million. On October 19, 2018, the Company announced a NCIB, commencing October 24, 2018, to purchase up to 5.68 million Common Shares for cancellation on or before October 23, 2019. The Company completed this NCIB on October 23, 2019. On May 10, 2017, the Company announced a NCIB, commencing May 15, 2017, to purchase up to 4.38 million Common Shares in the open market for cancellation on or before May 14, 2018. The Company completed this NCIB on May 10, 2018. All purchases were made in accordance with the respective NCIB at prevailing market prices plus brokerage fees, or such other prices that were permitted by the Toronto Stock Exchange ("TSX"), with consideration allocated to "Share capital" up to the average carrying amount of the shares and any excess allocated to "Retained earnings". The following table provides activities under the share repurchase programs for each of the years ended December 31: 2020 2019 2018 Number of Common Shares repurchased (1) 3,973,076 3,794,149 4,683,162 Weighted-average price per share (2) $ 371.74 $ 300.65 $ 240.68 Amount of repurchase (in millions) (2) $ 1,477 $ 1,141 $ 1,127 (1) Includes shares repurchased but not yet cancelled at year end. (2) Includes brokerage fees.

Change in Non-Cash Working Capi

Change in Non-Cash Working Capital Balances Related to Operations	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Change in Non-Cash Working Capital Balances Related to Operations	Change in non-cash working capital balances related to operations (in millions of Canadian dollars) 2020 2019 2018 (Use) source of cash: Accounts receivable, net $ (61) $ 27 $ (107) Materials and supplies (15) (8) (11) Other current assets (5) (24) 30 Accounts payable and accrued liabilities (308) (21) 153 Change in non-cash working capital $ (389) $ (26) $ 65

Pensions and Other Benefits

Pensions and Other Benefits	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Pensions and Other Benefits	Pensions and other benefitsThe Company has both defined benefit (“DB”) and defined contribution (“DC”) pension plans. At December 31, 2020, the Canadian pension plans represent nearly all of total combined pension plan assets and nearly all of total combined pension plan obligations. The DB plans provide for pensions based principally on years of service and compensation rates near retirement. Pensions for Canadian pensioners are partially indexed to inflation. Annual employer contributions to the DB plans, which are actuarially determined, are made on the basis of being not less than the minimum amounts required by federal pension supervisory authorities. The Company has other benefit plans including post-retirement health and life insurance for pensioners, and post-employment long-term disability and workers’ compensation benefits, which are based on Company-specific claims. At December 31, 2020, the Canadian other benefits plans represent nearly all of total combined other plan obligations. The Audit and Finance Committee of the Board of Directors has approved an investment policy that establishes long-term asset mix targets which take into account the Company’s expected risk tolerances. Pension plan assets are managed by a suite of independent investment managers, with the allocation by manager reflecting these asset mix targets. Most of the assets are actively managed with the objective of outperforming applicable benchmarks. In accordance with the investment policy, derivative instruments may be used by investment managers to hedge or adjust existing or anticipated exposures. To develop the expected long-term rate of return assumption used in the calculation of net periodic benefit cost applicable to the market-related value of plan assets, the Company considers the expected composition of the plans’ assets, past experience, and future estimates of long-term investment returns. Future estimates of investment returns reflect the long-term return expectation for fixed income, public equity, real estate, infrastructure, private debt, and absolute return investments, and the expected added value (relative to applicable benchmark indices) from active management of pension fund assets. The Company has elected to use a market-related value of assets for the purpose of calculating net periodic benefit cost, developed from a five The benefit obligation is discounted using a discount rate that is a blended yield to maturity for a hypothetical portfolio of high-quality debt instruments with cash flows matching projected benefit payments. The discount rate is determined by management. Net periodic benefit cost The elements of net periodic benefit cost for DB pension plans and other benefits recognized in the year include the following components: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2018 2020 2019 2018 Current service cost (benefits earned by employees) $ 140 $ 107 $ 120 $ 12 $ 11 $ 12 Other components of net periodic benefit cost (recovery): Interest cost on benefit obligation 406 450 438 17 20 19 Expected return on fund assets (945) (947) (955) — — — Recognized net actuarial loss 177 84 114 4 12 2 Amortization of prior service costs (1) (1) (2) — 1 — Total other components of net periodic benefit (recovery) cost (363) (414) (405) 21 33 21 Net periodic benefit (recovery) cost $ (223) $ (307) $ (285) $ 33 $ 44 $ 33 Projected benefit obligation, fund assets, and funded status Information about the Company’s DB pension plans and other benefits, in aggregate, is as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Change in projected benefit obligation: Benefit obligation at January 1 $ 12,610 $ 11,372 $ 541 $ 501 Current service cost 140 107 12 11 Interest cost 406 450 17 20 Employee contributions 42 41 — — Benefits paid (653) (646) (34) (34) Foreign currency changes (5) (10) — — Plan amendments and other 3 — — — Actuarial loss 1,256 1,296 17 43 Projected benefit obligation at December 31 $ 13,799 $ 12,610 $ 553 $ 541 The net actuarial losses for Pensions and Other benefits in 2020 were primarily due to the decrease in discount rate from 3.25% to 2.58%. The net actuarial losses for Pensions and Other benefits in 2019 were primarily due to the decrease in discount rate from 4.01% to 3.25%. Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Change in fund assets: Fair value of fund assets at January 1 $ 13,319 $ 12,349 $ 5 $ 4 Actual return on fund assets 1,634 1,528 — 1 Employer contributions 27 53 34 34 Employee contributions 42 41 — — Benefits paid (653) (646) (34) (34) Foreign currency changes (4) (6) — — Fair value of fund assets at December 31 $ 14,365 $ 13,319 $ 5 $ 5 Funded status – plan surplus (deficit) $ 566 $ 709 $ (548) $ (536) The table below shows the aggregate pension projected benefit obligation and aggregate fair value of plan assets for pension plans with fair value of plan assets in excess of projected benefit obligations (i.e. surplus), and for pension plans with projected benefit obligations in excess of fair value of plan assets (i.e. deficit): 2020 2019 (in millions of Canadian dollars) Pension Pension Pension Pension Projected benefit obligation at December 31 $ (13,220) $ (579) $ (12,076) $ (534) Fair value of fund assets at December 31 14,114 251 13,079 240 Funded Status $ 894 $ (328) $ 1,003 $ (294) The DB pension plans’ accumulated benefit obligation as at December 31, 2020 was $13,528 million (2019 – $12,201 million). The accumulated benefit obligation is calculated on a basis similar to the projected benefit obligation, except no future salary increases are assumed in the projection of future benefits. For pension plans with accumulated benefit obligations in excess of fair value of plan assets (i.e. deficit), the aggregate pension accumulated benefit obligation as at December 31, 2020 was $443 million (2019 – $419 million) and the aggregate fair value of plan assets as at December 31, 2020 was $187 million (2019 –$186 million). All Other benefits plans were in a deficit position at December 31, 2020 and 2019. Pension asset and liabilities in the Company’s Consolidated Balance Sheets Amounts recognized in the Company’s Consolidated Balance Sheets are as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Pension asset $ 894 $ 1,003 $ — $ — Accounts payable and accrued liabilities (11) (11) (33) (34) Pension and other benefit liabilities (317) (283) (515) (502) Total amount recognized $ 566 $ 709 $ (548) $ (536) The measurement date used to determine the plan assets and the accrued benefit obligation is December 31. The most recent actuarial valuation for pension funding purposes for the Company’s main Canadian pension plan was performed as at January 1, 2020. During 2021, the Company expects to file with the pension regulator a new valuation performed as at January 1, 2021. Accumulated other comprehensive loss Amounts recognized in accumulated other comprehensive loss are as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Net actuarial loss: Other than deferred investment gains $ 3,960 $ 3,434 $ 104 $ 91 Deferred investment gains (95) 41 — — Prior service cost 5 1 1 1 Deferred income tax (1,070) (964) (27) (24) Total (Note 8) $ 2,800 $ 2,512 $ 78 $ 68 Actuarial assumptions Weighted-average actuarial assumptions used were approximately: (percentages) 2020 2019 2018 Benefit obligation at December 31: Discount rate 2.58 3.25 4.01 Projected future salary increases 2.75 2.75 2.75 Health care cost trend rate 5.00 (1) 5.50 (1) 6.00 (1) Benefit cost for year ended December 31: Discount rate 3.25 4.01 3.80 Expected rate of return on fund assets (3) 7.25 7.50 7.75 Projected future salary increases 2.75 2.75 2.75 Health care cost trend rate 5.50 (1) 6.00 (1) 7.00 (2) (1) The health care cost trend rate was assumed to be 6.00% in 2019 and 5.50% in 2020 and is assumed to be 5.00% per year in 2021 and thereafter. (2) The health care cost trend rate was previously assumed to be 7.00% in 2018, and then decreasing by 0.50% per year to an ultimate rate of 5.00% per year in 2022 and thereafter. (3) The expected rate of return on fund assets that will be used to compute the 2021 net periodic benefit credit is 6.90%. Plan assets Plan assets are recorded at fair value. The major asset categories are public equity securities, fixed income securities, real estate, infrastructure, absolute return investments, and private debt. The fair values of the public equity and fixed income securities are primarily based on quoted market prices. Real estate and infrastructure values are based on the value of each fund’s assets as calculated by the fund manager, generally using third party appraisals or discounted cash flow analysis and taking into account current market conditions and recent sales transactions where practical and appropriate. Private debt values are based on the value of each fund’s assets as calculated by the fund manager taking into account current market conditions and reviewed annually by external parties. Absolute return investments are a portfolio of units of externally managed hedge funds and are valued by the fund administrators. The Company’s pension plan asset allocation, the weighted-average asset allocation targets, and the weighted average policy range for each major asset class at year end were as follows: Percentage of plan assets Asset allocation (percentage) Asset allocation target Policy range 2020 2019 Cash and cash equivalents 1.2 0 – 10 2.0 0.9 Fixed income 24.1 20 – 40 28.1 24.6 Public equity 45.1 35 – 55 49.3 54.5 Real estate and infrastructure 9.8 4 – 13 6.3 6.8 Private debt 9.8 4 – 13 3.3 2.4 Absolute return 10.0 4 – 13 11.0 10.8 Total 100.0 100.0 100.0 Summary of the assets of the Company’s DB pension plans The following is a summary of the assets of the Company’s DB pension plans at December 31, 2020 and 2019. As of December 31, 2020 and 2019, there were no plan assets classified as Level 3 valued investments. Assets Measured at Fair Value Investments measured at NAV (1) Total Plan (in millions of Canadian dollars) Quoted prices in Significant other observable inputs (Level 2) December 31, 2020 Cash and cash equivalents $ 219 $ — $ — $ 219 Fixed income Government bonds (2) 284 1,699 — 1,983 Corporate bonds (2) 691 1,144 — 1,835 Mortgages (3) 220 5 — 225 Public equities Canada 1,183 — — 1,183 U.S. and international 5,871 28 — 5,899 Real estate (4) — — 704 704 Infrastructure (5) — — 199 199 Private debt (6) — — 465 465 Derivative instruments (7) — 71 — 71 Absolute return (8) Funds of hedge funds — — 1,560 1,560 Multi-strategy funds — — 22 22 $ 8,468 $ 2,947 $ 2,950 $ 14,365 December 31, 2019 Cash and cash equivalents $ 112 $ — $ — $ 112 Fixed income Government bonds (2) 233 1,857 — 2,090 Corporate bonds (2) 273 819 — 1,092 Mortgages (3) 159 5 — 164 Public equities Canada 1,351 — — 1,351 U.S. and international 5,883 22 — 5,905 Real estate (4) — — 724 724 Infrastructure (5) — — 187 187 Private debt (6) — — 313 313 Derivative instruments (7) — (59) — (59) Absolute return (8) Funds of hedge funds — — 1,418 1,418 Multi-strategy funds — — 22 22 $ 8,011 $ 2,644 $ 2,664 $ 13,319 (1) Investments measured at net asset value ("NAV"): Amounts are comprised of certain investments measured using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. (2) Government & Corporate Bonds: Fair values for bonds are based on market prices supplied by independent sources as of the last trading day. (3) Mortgages: The fair values of mortgages are based on current market yields of financial instruments of similar maturity, coupon and risk factors. (4) Real estate: Real estate fund values are based on the NAV of the funds that invest directly in real estate investments. The values of the investments have been estimated using the capital accounts representing the plan’s ownership interest in the funds. Of the total, $580 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $606 million). The remaining $124 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying real estate investments (2019 – $118 million). As at December 31, 2020, there are $32 million of unfunded commitments for real estate investments (December 31, 2019 – $35 million). (5) Infrastructure: Infrastructure fund values are based on the NAV of the funds that invest directly in infrastructure investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $112 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $119 million). The remaining $87 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying infrastructure investments (2019 – $68 million). As at December 31, 2020, there are $491 million of unfunded commitments for infrastructure investments (December 31, 2019 – $286 million). (6) Private debt: Private debt fund values are based on the NAV of the funds that invest directly in private debt investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $154 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $154 million). The remaining $311 million is not subject to redemption and is normally returned through distributions as a result of the repayment of the underlying loans (2019 - $159 million). As at December 31, 2020, there are $533 million of unfunded commitments for private debt investments (December 31, 2019 – $392 million). (7) Derivatives: The investment managers may utilize the following derivative instruments: equity futures to replicate equity index returns (Level 2); currency forwards to partially hedge foreign currency exposures (Level 2); bond forwards to reduce asset/liability interest rate risk exposures (Level 2); interest rate swaps to manage duration and interest rate risk (Level 2); credit default swaps to manage credit risk (Level 2); and options to manage interest rate risk and volatility (Level 2). The Company may utilize derivatives directly, but only for the purpose of hedging foreign currency exposures. As at December 31, 2020, there are currency forwards with a notional value of $1,041 million (December 31, 2019 – $334 million) and a fair value of $73 million (December 31, 2019 – $13 million). The fixed income investment manager utilizes a portfolio of bond forwards for the purpose of reducing asset/liability interest rate exposure. As at December 31, 2020, there are bond forwards with a notional value of $3,540 million ( December 31, 2019 – $3,269 million) and a negative fair value of $2 million (December 31, 2019 – $(72) million). (8) Absolute return: The value of absolute return fund investments is based on the NAV reported by the fund administrators. The funds have different redemption policies with redemption notice periods varying from 60 to 95 days and frequencies ranging from monthly to triennially. Additional plan assets information The Company's primary investment objective for pension plan assets is to achieve a long–term return, net of all fees and expenses, that is sufficient for the plan's assets to satisfy the current and future obligations to plan beneficiaries, while minimizing the financial impact on the Company. In identifying the asset allocation ranges, consideration was given to the long-term nature of the underlying plan liabilities, the solvency and going-concern financial position of the plan, long-term return expectations, and the risks associated with key asset classes as well as the relationships of returns on key asset classes with each other, inflation, and interest rates. When advantageous and with due consideration, derivative instruments may be utilized by investment managers, provided the total value of the underlying assets represented by financial derivatives (excluding currency forwards, liability hedging derivatives in fixed income portfolios, and derivatives held by absolute return funds) is limited to 30% of the market value of the fund. The funded status of the plans is exposed to fluctuations in interest rates, which affects the relative values of the plans' liabilities and assets. In order to mitigate interest rate risk, the Company's main Canadian defined benefit pension plan utilizes a liability driven investment strategy in its fixed income portfolio, which uses a combination of long duration bonds and derivatives to hedge interest rate risk, managed by the investment manager. At December 31, 2020, the plan's solvency funded position was 47% hedged against interest rate risk (2019 – 45%). When investing in foreign securities, the plans are exposed to foreign currency risk; the effect of which is included in the valuation of the foreign securities. At December 31, 2020, the plans were 33% exposed to the U.S. dollar net of currency forwards (40% excluding the currency forwards), 6% exposed to the Euro, and 14% exposed to various other currencies. At December 31, 2019, the plans were 39% exposed to the U.S. dollar net of currency forwards (41% excluding the currency forwards), 6% exposed to the Euro, and 14% exposed to various other currencies. At December 31, 2020, fund assets included 109,008 of the Common Shares of the Company (2019 – 119,758) at a market value of $48 million (2019 – $40 million). Estimated future benefit payments The estimated future DB pension and other benefit payments to be paid by the plans for each of the next five years and the subsequent five-year period are as follows: (in millions of Canadian dollars) Pensions Other benefits 2021 $ 632 $ 33 2022 629 31 2023 631 31 2024 633 30 2025 635 30 2026-2030 3,203 142 The benefit payments from the Canadian registered and U.S. qualified DB pension plans are payable from their respective pension funds. Benefit payments from the supplemental pension plan and from the other benefits plans are payable directly from the Company. Defined contribution plan Canadian non-unionized employees hired prior to July 1, 2010 had the option to participate in the Canadian DC plan. All Canadian non-unionized employees hired after such date must participate in this plan. Employee contributions are based on a percentage of salary. The Company matches employee contributions to a maximum percentage each year. Effective July 1, 2010, a new U.S. DC plan was established. All U.S. non-unionized employees hired after such date must participate in this plan. Employees do not contribute to the plan. The Company annually contributes a percentage of salary. The DC plans provide a pension based on total employee, where appropriate, and employer contributions plus investment income earned on those contributions. In 2020, the net cost of the DC plans, which generally equals the employer’s required contribution, was $12 million (2019 – $11 million; 2018 – $10 million). Contributions to multi-employer plans Some of the Company’s unionized employees in the U.S. are members of a U.S. national multi-employer benefit plan. Contributions made by the Company to this plan in 2020 in respect of post-retirement medical benefits were $3 million (2019 – $3 million; 2018 – $3 million).

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-based compensationAt December 31, 2020, the Company had several stock-based compensation plans including stock option plans, various cash-settled liability plans, and an employee share purchase plan. These plans resulted in an expense of $170 million in 2020 (2019 – $133 million; 2018 – $75 million). A. Stock option plan The following table summarizes the Company’s stock option plan as at December 31, 2020: Options outstanding Non-vested options Number of Weighted-average Number of Weighted-average Outstanding, January 1, 2020 1,416,346 $ 199.12 761,784 $ 53.54 Granted 217,240 $ 344.04 217,240 $ 69.00 Exercised (232,034) $ 162.87 N/A N/A Vested N/A N/A (188,108) $ 50.91 Forfeited (13,839) $ 271.75 (13,839) $ 58.29 Expired (347) $ 168.84 N/A N/A Outstanding, December 31, 2020 1,387,366 $ 225.20 777,077 $ 58.40 Vested or expected to vest at December 31, 2020 (1) 1,366,649 $ 223.98 N/A N/A Exercisable, December 31, 2020 610,289 $ 177.65 N/A N/A (1) As at December 31, 2020, the weighted-average remaining term of vested or expected to vest options was 4.5 years with an aggregate intrinsic value of $297 million . The following table provides the number of stock options outstanding and exercisable as at December 31, 2020 by range of exercise price and their related intrinsic aggregate value, and for options outstanding, the weighted-average years to expiration. The table also provides the aggregate intrinsic value for in-the-money stock options, which represents the amount that would have been received by option holders had they exercised their options on December 31, 2020 at the Company’s closing stock price of $441.53. Options outstanding Options exercisable Range of exercise prices Number of Weighted-average Weighted-average Aggregate Number of Weighted-average Aggregate $65.06 - $188.78 342,773 3.4 $ 141.26 $ 103 342,773 $ 141.26 $ 103 $188.79 - $214.58 327,811 3.1 $ 196.82 $ 80 109,375 $ 203.83 $ 26 $214.59 - $261.88 394,953 4.4 $ 244.17 $ 78 134,845 $ 232.54 $ 28 $261.89 - $411.37 321,829 5.8 $ 320.21 $ 39 23,296 $ 272.56 $ 4 Total (1) 1,387,366 4.2 $ 225.20 $ 300 610,289 $ 177.65 $ 161 (1) As at December 31, 2020, the total number of in-the-money stock options outstanding was 1,387,366 with a weighted-average exercise price of $225.20. The weighted-average years to expiration of exercisable stock options is 3.6 years. Pursuant to the employee plan, options may be exercised upon vesting, which is between 12 months and 48 months after the grant date, and will expire after seven years. Certain stock options granted in 2019 and 2018 vest upon the achievement of specific performance criteria. Under the fair value method, the fair value of the stock options at grant date was approximately $15 million for options issued in 2020 (2019 – $14 million; 2018 – $16 million). The weighted-average fair value assumptions were approximately: 2020 2019 2018 Expected option life (years) (1) 4.75 5.00 5.00 Risk-free interest rate (2) 1.28 % 2.22 % 2.22 % Expected stock price volatility (3) 23.14 % 25.04 % 24.81 % Expected annual dividends per share (4) $ 3.3200 $ 2.6191 $ 2.3854 Expected forfeiture rate (5) 4.41 % 6.05 % 4.70 % Weighted-average grant date fair value of options granted during the year $ 69.00 $ 63.69 $ 55.63 (1) Represents the period of time that awards are expected to be outstanding. Historical data on exercise behaviour or, when available, specific expectations regarding future exercise behaviour were used to estimate the expected life of the option. (2) Based on the implied yield available on zero-coupon government issues with an equivalent term commensurate with the expected term of the option. (3) Based on the historical volatility of the Company’s stock price over a period commensurate with the expected term of the option. (4) Determined by the current annual dividend at the time of grant. The Company does not employ different dividend yields throughout the contractual term of the option. On July 21, 2020, the Company announced an increase in its quarterly dividend to $0.9500 per share, representing $3.8000 on an annual basis. (5) The Company estimates forfeitures based on past experience. The rate is monitored on a periodic basis. In 2020, the expense for stock options (regular and performance) was $16 million (2019 – $14 million; 2018 – $10 million). At December 31, 2020, there was $12 million of total unrecognized compensation related to stock options which is expected to be recognized over a weighted-average period of approximately 1.1 years. The total fair value of shares vested for the stock option plan during 2020 was $10 million (2019 – $8 million; 2018 – $11 million). The following table provides information related to all options exercised in the stock option plan during the years ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Total intrinsic value $ 52 $ 63 $ 17 Cash received by the Company upon exercise of options 52 26 24 B. Other share-based plans Performance share unit plans During 2020, the Company issued 97,998 PSUs with a grant date fair value of approximately $34 million and 10,029 PDSUs with a grant date fair value, including value of expected future matching units, of approximately $4 million. PSUs and PDSUs attract dividend equivalents in the form of additional units, based on dividends paid on the Company's Common Shares, and vest approximately three years after the grant date contingent upon CP’s performance ("performance factor"). The fair value of these PSUs and PDSUs is measured periodically until settlement using closing share price on the date of measurement. The fair value of units that are probable of vesting based on forecasted performance factors over the three-year performance period is recognized as expense in the Consolidated Statements of Income. Vested PSUs are settled in cash. Vested PDSUs are settled in cash pursuant to the DSU plan and are eligible for a 25% match if the holder has not exceeded their share ownership requirements, and are paid out only when the holder ceases their employment with CP. The performance period for PSUs and PDSUs issued in 2020 is January 1, 2020 to December 31, 2022, and the performance factors are Return on Invested Capital ("ROIC"), Total Shareholder Return ("TSR") compared to the S&P/TSX 60 Index, and TSR compared to Class I railways. The performance period for 133,681 PSUs issued in 2019 is January 1, 2019 to December 31, 2021, and the performance factors for these PSUs are ROIC, TSR compared to the S&P/TSX 60 Index, and TSR compared to Class I railways. The performance factors for the remaining 579 PSUs are annual revenue for the fiscal year 2020, diluted earnings per share for the fiscal year 2020, and share price appreciation. The performance period for 125,280 PSUs issued in 2018 is January 1, 2018 to December 31, 2020, and the performance factors for these PSUs were ROIC, TSR compared to the S&P/TSX Capped Industrial Index, and TSR compared to the S&P 1500 Road and Rail Index. The resulting estimated payout on these awards was 200% on 113,769 total outstanding awards representing a total fair value of $98 million at December 31, 2020, calculated using the Company's average share price of the last 30 trading days preceding December 31, 2020. The performance factors for the remaining 36,975 PSUs were annual revenue for the fiscal year 2020, diluted earnings per share for the fiscal year 2020, and share price appreciation. The performance period for PSUs issued in 2017 was January 1, 2017 to December 31, 2019, and the performance factors for these PSUs were ROIC, TSR compared to the S&P/TSX Capped Industrial Index, and TSR compared to the S&P 1500 Road and Rail Index. The resulting payout was 193% of the outstanding units multiplied by the Company's average share price calculated using the last 30 trading days preceding December 31, 2019. In the first quarter of 2020, payouts occurred on the total outstanding awards, including dividends reinvested, totalling $76 million on 121,225 outstanding awards. The following table summarizes information related to the Company’s PSUs and PDSUs as at December 31: 2020 2019 Outstanding, January 1 403,136 395,048 Granted 108,027 134,260 Units, in lieu of dividends 3,843 4,032 Settled (121,225) (117,228) Forfeited (11,912) (12,976) Outstanding, December 31 381,869 403,136 In 2020, the expense for PSUs and PDSUs was $121 million (2019 – $89 million; 2018 – $54 million). At December 31, 2020, there was $51 million of total unrecognized compensation related to these awards which is expected to be recognized over a weighted-average period of approximately 1.4 years. Deferred share unit plan The Company established the DSU plan as a means to compensate and assist in attaining share ownership targets set for certain key employees and Directors. A DSU entitles the holder to receive, upon redemption, a cash payment equivalent to the Company's average share price using the 10 trading days prior to redemption. DSUs vest over various periods of up to 36 months and are only redeemable for a specified period after employment is terminated. Senior managers may elect to receive DSUs in lieu of annual bonus cash payments in the bonus deferral program. In addition, senior managers will be granted a 25% company match of DSUs when deferring cash to DSUs to meet ownership targets. The election to receive eligible payments in DSUs is no longer available to a participant when the value of the participant’s DSUs is sufficient to meet the Company’s stock ownership guidelines. Senior managers have five years to meet their ownership targets. The expense for DSUs is recognized over the vesting period for both the initial subscription price and the change in value between reporting periods. The following table summarizes information related to the DSUs as at December 31: 2020 2019 Outstanding, January 1 161,219 152,760 Granted 19,041 19,912 Units, in lieu of dividends 1,511 1,608 Settled (26,788) (12,110) Forfeited (172) (951) Outstanding, December 31 154,811 161,219 During 2020, the Company granted 19,041 DSUs with a grant date fair value of approximately $7 million. In 2020, the expense for DSUs was $21 million (2019 – $20 million expense; 2018 – $4 million expense). At December 31, 2020, there was $1 million of total unrecognized compensation related to DSUs which is expected to be recognized over a weighted-average period of approximately 1.3 years. Summary of share-based liabilities paid The following table summarizes the total share-based liabilities paid for each of the years ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Plan PSUs $ 76 $ 54 $ 30 DSUs 9 4 6 Other 1 — 1 Total $ 86 $ 58 $ 37 C. Employee share purchase plan The Company has an employee share purchase plan whereby both employee and the Company contributions are used to purchase shares on the open market for employees. The Company’s contributions are expensed over the one year vesting period. Under the plan, the Company matches $1 for every $3 contributed by employees up to a maximum employee contribution of 6% of annual salary.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2020
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entities	Variable interest entities The Company leases equipment from certain trusts, which have been determined to be variable interest entities financed by a combination of debt and equity provided by unrelated third parties. The lease agreements, which are classified as operating leases, have fixed price purchase options which create the Company’s variable interests and result in the trusts being considered variable interest entities. Maintaining and operating the leased assets according to specific contractual obligations outlined in the terms of the lease agreements and industry standards is the Company’s responsibility. The rigour of the contractual terms of the lease agreements and industry standards are such that the Company has limited discretion over the maintenance activities associated with these assets. As such, the Company concluded these terms do not provide the Company with the power to direct the activities of the variable interest entities in a way that has a significant impact on the entities’ economic performance. The financial exposure to the Company as a result of its involvement with the variable interest entities is equal to the fixed lease payments due to the trusts. In 2020, lease payments after tax were $14 million. Future minimum lease payments, before tax, of $126 million will be payable over the next 10 years. The Company does not guarantee the residual value of the assets to the lessor; however, it must deliver to the lessor the assets in good operating condition, subject to normal wear and tear, at the end of the lease term. As the Company’s actions and decisions do not significantly affect the variable interest entities’ performance, and the Company’s fixed price purchase option is not considered to be potentially significant to the variable interest entities, the Company is not considered to be the primary beneficiary, and does not consolidate these variable interest entities.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and contingencies In the normal course of its operations, the Company becomes involved in various legal actions, including claims relating to injuries and damage to property. The Company maintains provisions it considers to be adequate for such actions. While the final outcome with respect to actions outstanding or pending at December 31, 2020 cannot be predicted with certainty, it is the opinion of management that their resolution will not have a material adverse effect on the Company’s business, financial position, or results of operations. However, an unexpected adverse resolution of one or more of these legal actions could have a material adverse effect on the Company's business, financial position, results of operations, or liquidity in a particular quarter or fiscal year. Commitments At December 31, 2020, the Company had committed to total future capital expenditures amounting to $547 million and operating expenditures relating to supplier purchase obligations, such as bulk fuel purchase agreements, locomotive maintenance and overhaul agreements, as well as agreements to purchase other goods and services amounting to approximately $1.7 billion for the years 2021–2032, of which CP estimates approximately $1.6 billion will be incurred in the next five years. Commitments related to leases, including minimum annual payments for the next five years and thereafter, are included in Note 19. Legal proceedings related to Lac-Mégantic rail accident On July 6, 2013, a train carrying petroleum crude oil operated by Montréal Maine and Atlantic Railway (“MMAR”) or a subsidiary, Montréal Maine & Atlantic Canada Co. (“MMAC” and collectively the “MMA Group”), derailed in Lac-Mégantic, Québec. The derailment occurred on a section of railway owned and operated by the MMA Group and while the MMA Group exclusively controlled the train. Following the derailment, MMAC sought court protection in Canada under the Companies’ Creditors Arrangement Act and MMAR filed for bankruptcy in the U.S. Plans of arrangement were approved in both Canada and the U.S. (the “Plans”), providing for the distribution of approximately $440 million amongst those claiming derailment damages. A number of legal proceedings, set out below, were commenced in Canada and the U.S. against CP and others: (1) Québec's Minister of Sustainable Development, Environment, Wildlife and Parks ordered various parties, including CP, to remediate the derailment site (the "Cleanup Order") and served CP with a Notice of Claim for $95 million for those costs. CP appealed the Cleanup Order and contested the Notice of Claim with the Administrative Tribunal of Québec. These proceedings are stayed pending determination of the Attorney General of Québec (“AGQ”) action (paragraph 2 below). (2) The AGQ sued CP in the Québec Superior Court claiming $409 million in damages, which was amended and reduced to $315 million (the “AGQ Action”). The AGQ Action alleges that: (i) CP was responsible for the petroleum crude oil from its point of origin until its delivery to Irving Oil Ltd.; and (ii) CP is vicariously liable for the acts and omissions of the MMA Group. (3) A class action in the Québec Superior Court on behalf of persons and entities residing in, owning or leasing property in, operating a business in, or physically present in Lac-Mégantic at the time of the derailment was certified against CP on May 8, 2015 (the "Class Action"). Other defendants including MMAC and Mr. Thomas Harding ("Harding") were added to the Class Action on January 25, 2017. The Class Action seeks unquantified damages, including for wrongful death, personal injury, property damage, and economic loss. (4) Eight subrogated insurers sued CP in the Québec Superior Court claiming approximately $16 million in damages, which was amended and reduced to approximately $15 million (the “Promutuel Action”), and two additional subrogated insurers sued CP claiming approximately $3 million in damages (the “Royal Action”). Both actions contain similar allegations as the AGQ Action. The actions do not identify the subrogated parties. As such, the extent of any overlap between the damages claimed in these actions and under the Plans is unclear. The Royal Action is stayed pending determination of the consolidated proceedings described below. On December 11, 2017, the AGQ Action, the Class Action and the Promutuel Action were consolidated. These consolidated claims are currently scheduled for a joint liability trial commencing on or around September 13, 2021, followed by a damages trial, if necessary. (5) Forty-eight plaintiffs (all individual claims joined in one action) sued CP, MMAC, and Harding in the Québec Superior Court claiming approximately $5 million in damages for economic loss and pain and suffering, and asserting similar allegations as in the Class Action and the AGQ Action. The majority of the plaintiffs opted-out of the Class Action and all but two are also plaintiffs in litigation against CP, described in paragraph 7 below. This action is stayed pending determination of the consolidated claims described above. (6) The MMAR U.S. bankruptcy estate representative commenced an action against CP in November 2014 in the Maine Bankruptcy Court claiming that CP failed to abide by certain regulations and seeking approximately U.S. $30 million in damages for MMAR’s loss in business value according to a recent report. This action asserts that CP knew or ought to have known that the shipper misclassified the petroleum crude oil and therefore should have refused to transport it. (7) The class and mass tort action commenced against CP in June 2015 in Texas (on behalf of Lac-Mégantic residents and wrongful death representatives) and the wrongful death and personal injury actions commenced against CP in June 2015 in Illinois and Maine, were all transferred and consolidated in Federal District Court in Maine (the “Maine Actions”). The Maine Actions allege that CP negligently misclassified and improperly packaged the petroleum crude oil. On CP’s motion, the Maine Actions were dismissed. The plaintiffs are appealing the dismissal decision, which is pending. (8) The trustee for the wrongful death trust commenced Carmack Amendment claims against CP in North Dakota Federal Court, seeking to recover approximately U.S. $6 million for damaged rail cars and lost crude and reimbursement for the settlement paid by the consignor and the consignee under the Plans (alleged to be U.S. $110 million and U.S. $60 million, respectively). The Court issued an Order on August 6, 2020 granting and denying in parts the parties' summary judgment motions which has been reviewed and confirmed following motions by the parties for clarification and reconsideration. This action is scheduled for trial on September 21, 2021. At this stage of the proceedings, any potential responsibility and the quantum of potential losses cannot be determined. Nevertheless, CP denies liability and is vigorously defending these proceedings.

Guarantees

Guarantees	12 Months Ended
	Dec. 31, 2020
Guarantees [Abstract]
Guarantees	Guarantees In the normal course of operating the railway, the Company enters into contractual arrangements that involve providing certain guarantees, which extend over the term of the contracts. These guarantees include, but are not limited to: • guarantees to pay other parties in the event of the occurrence of specified events, including damage to equipment, in relation to assets used in the operation of the railway through operating leases, rental agreements, easements, trackage, and interline agreements; and • indemnifications of certain tax-related payments incurred by lessors and lenders. The maximum amount that could be payable under these guarantees, excluding residual value guarantees, cannot be reasonably estimated due to the nature of certain of these guarantees. All or a portion of amounts paid under guarantees to other parties in the event of the occurrence of specified events could be recoverable from other parties or through insurance. The Company has accrued for all guarantees that it expects to pay. At December 31, 2020, these accruals amounted to $18 million (2019 – $10 million), and are recorded in “Accounts payable and accrued liabilities". Indemnifications Pursuant to a trust and custodial services agreement with the trustee of the Canadian Pacific Railway Company Pension Plan, the Company has undertaken to indemnify and save harmless the trustee, to the extent not paid by the fund, from any and all taxes, claims, liabilities, damages, costs, and expenses arising out of the performance of the trustee’s obligations under the agreement, except as a result of misconduct by the trustee. The indemnity includes liabilities, costs, or expenses relating to any legal reporting or notification obligations of the trustee with respect to the defined benefit and defined contribution options of the pension plans, or otherwise with respect to the assets of the pension plans that are not part of the fund. The indemnity survives the termination or expiry of the agreement with respect to claims and liabilities arising prior to the termination or expiry. At December 31, 2020, the Company had not recorded a liability associated with this indemnification as it does not expect to make any payments pertaining to it.

Segmented and Geographic Inform

Segmented and Geographic Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segmented and Geographical Information	Segmented and geographic information Operating segment The Company operates in only one operating segment: rail transportation. Operating results by geographic areas, railway corridors, or other lower-level components or units of operation are not reviewed by the Company’s chief operating decision-maker to make decisions about the allocation of resources to, or the assessment of performance of, such geographic areas, corridors, components, or units of operation. In the years ended December 31, 2020, 2019, and 2018, no one customer comprised more than 10% of total revenues and accounts receivable. Geographic information All of the company's revenue and long-lived assets excluding financial instruments are held within Canada and the United States. (in millions of Canadian dollars) Canada United States Total 2020 Revenues $ 5,829 $ 1,881 $ 7,710 Long-term assets excluding financial instruments and pension assets 14,258 7,165 21,423 2019 Revenues 5,675 2,117 7,792 Long-term assets excluding financial instruments and pension assets 13,131 7,020 20,151 2018 Revenues 5,232 2,084 7,316 Long-term assets excluding financial instruments and pension assets 12,133 6,759 18,892

Selected Quarterly Data (Unaudi

Selected Quarterly Data (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Data (Unaudited)	Selected quarterly data (unaudited) For the quarter ended 2020 2019 (in millions of Canadian dollars, except per share data) Dec. 31 Sep. 30 Jun. 30 Mar. 31 Dec. 31 Sep. 30 Jun. 30 Mar. 31 Total revenues $ 2,012 $ 1,863 $ 1,792 $ 2,043 $ 2,069 $ 1,979 $ 1,977 $ 1,767 Operating income 928 779 770 834 890 869 822 543 Net income 802 598 635 409 664 618 724 434 Basic earnings per share (1) $ 5.97 $ 4.42 $ 4.68 $ 2.99 $ 4.84 $ 4.47 $ 5.19 $ 3.10 Diluted earnings per share (1) $ 5.95 $ 4.41 $ 4.66 $ 2.98 $ 4.82 $ 4.46 $ 5.17 $ 3.09 (1) Earnings per share for the four quarters combined may not equal earnings per share for the year due to rounding.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	Schedule II – Valuation and Qualifying Accounts (in millions of Canadian dollars) Beginning balance at January 1 Additions charged to expenses Payments and other reductions Impact of FX Ending Accruals for personal injury and other claims provision (1) 2018 $ 118 $ 93 $ (60) $ 1 $ 152 2019 $ 152 $ 142 $ (152) $ (1) $ 141 2020 $ 141 $ 105 $ (119) $ (1) $ 126 Environmental liabilities 2018 $ 78 $ 6 $ (7) $ 5 $ 82 2019 $ 82 $ 6 $ (8) $ (3) $ 77 2020 $ 77 $ 10 $ (6) $ (1) $ 80 (1) Includes WCB, FELA, occupational, damage, and other.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Accounting, US GAAP	Accounting principles generally accepted in the United States of America (“GAAP”) These Consolidated Financial Statements are expressed in Canadian dollars and have been prepared in accordance with GAAP.
Principles of consolidation	Principles of consolidation These Consolidated Financial Statements include the accounts of CP and all its subsidiaries. The Company’s investments in which it has significant influence are accounted for using the equity method. Distributions received from equity method investees are classified using the nature of the distribution approach for cash flow presentation purposes, whereby distributions received are classified based on the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities). All intercompany accounts and transactions have been eliminated.
Use of estimates	Use of estimates The preparation of these Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of revenues and expenses during the year, the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements. Management regularly reviews its estimates, including those related to environmental liabilities, pensions and other benefits, depreciable lives of properties, deferred income tax assets and liabilities, as well as legal and personal injury liabilities based upon currently available information. Actual results could differ from these estimates.
Revenue recognition	Revenue recognition Revenue is recognized when obligations under the terms of a contract with a customer are satisfied. Revenue is measured as the amount of consideration the Company expects to receive in exchange for providing services. Government imposed taxes that the Company collects concurrent with revenue generating activities are excluded from revenue. In the normal course of business, the Company does not generate any material revenue through acting as an agent for other entities. The Company provides rail freight transportation services to a wide variety of customers and transports bulk commodities, merchandise freight and intermodal traffic. The Company signs master service agreements with customers that dictate future services the Company is to perform for a customer at the time a bill of lading or service request is received. Each bill of lading or service request represents a separate distinct performance obligation that the Company is obligated to satisfy. The transaction price is generally in the form of a fixed fee determined at the inception of the bill of lading or service request. The Company allocates the transaction price to each distinct performance obligation based on the estimated standalone selling price for each performance obligation. As each bill of lading or service request represents a separate distinct performance obligation, the estimated standalone selling price is assessed at an observable price which is fair market value. Certain customer agreements include variable consideration in the form of rebates, discounts, or incentives. The expected value method is used to estimate variable consideration and is allocated to the applicable performance obligation and is recognized when the related performance obligation is satisfied. Additionally, the Company offers published rates for services through public tariff agreements in which a customer can request service, triggering a performance obligation the Company must satisfy. Railway freight revenues are recognized over time as services are provided based on the percentage of completed service method. Volume rebates to customers are accrued as a reduction of freight revenues based on estimated volumes and contract terms as freight service is provided. Freight revenues also include certain ancillary and other services provided in association with the performance of rail freight movements. Revenues from these activities are not material and therefore have been aggregated with the freight revenues from customer contracts with which they are associated. Non-freight revenues, including revenues earned from passenger service operators, switching fees, and revenues from logistics services, are recognized at the point in time the services are provided or when the performance obligations are satisfied. Non-freight revenues also include leasing revenues.
Income taxes	Income taxes The Company follows the liability method of accounting for income taxes. Deferred income tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The effect of a change in income tax rates on deferred income tax assets and liabilities is recognized in income in the period during which the change occurs. When appropriate, the Company records a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, CP considers whether it is more likely than not that all or some portion of CP’s deferred tax assets will not be realized, based on management’s judgment using available evidence about future events. At times, tax benefit claims may be challenged by a tax authority. Tax benefits are recognized only for tax positions that are more likely than not sustainable upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for “unrecognized tax benefits” is recorded for any tax benefits claimed in CP’s tax returns that do not meet these recognition and measurement standards. Investment and other similar tax credits are deferred on the Company's Consolidated Balance Sheets and amortized to “Income tax expense” as the related asset is recognized in income. Income tax recovery or expense on items in "Accumulated other comprehensive loss" are recognized in "Income tax expense" as the related item is recognized in income.
Earnings per share	Earnings per share Basic earnings per share are calculated using the weighted-average number of the Company's Common Shares ("Common Shares") outstanding during the year. Diluted earnings per share are calculated using the treasury stock method for determining the dilutive effect of options.
Foreign currency translation	Foreign currency translation Assets and liabilities denominated in foreign currencies, other than those held through foreign subsidiaries, are translated into Canadian dollars at the year-end exchange rate for monetary items and at the historical exchange rates for non-monetary items. Foreign currency revenues and expenses are translated at the exchange rates in effect on the dates of the related transactions. Foreign exchange ("FX") gains and losses, other than those arising from the translation of the Company’s net investment in foreign subsidiaries, are included in income. The accounts of the Company’s foreign subsidiaries are translated into Canadian dollars using the year-end exchange rate for assets and liabilities and the average exchange rates during the year for revenues, expenses, gains, and losses. FX gains and losses arising from the translation of the foreign subsidiaries’ assets and liabilities are included in “Other comprehensive loss”. A portion of U.S. dollar-denominated long-term debt has been designated as a hedge of the net investment in foreign subsidiaries. As a result, unrealized FX gains and losses on U.S. dollar-denominated long-term debt, designated as a hedge, are offset against FX gains and losses arising from the translation of foreign subsidiaries’ accounts in “Other comprehensive loss”.
Cash and cash equivalents	Cash and cash equivalents Cash and cash equivalents include highly liquid short-term investments that are readily convertible to cash with original maturities of three months or less, but excludes cash and cash equivalents subject to restrictions.
Accounts receivable	Accounts receivable Accounts receivable from customers are recognized initially at fair value and subsequently measured at amortized cost less allowance for expected credit losses. Losses on accounts receivable are estimated based on historical credit loss experience of receivables with similar risk characteristics. Historical loss experience is adjusted to reflect any management expectations that current or future conditions will differ from conditions that existed for the period over which historical information is evaluated.
Materials and supplies	Materials and supplies Materials and supplies are carried at the lower of average cost or market value and consist primarily of fuel and parts used in the repair and maintenance of track structures, equipment, locomotives and freight cars.
Properties	Properties Fixed asset additions and major renewals are recorded at cost, including direct costs, attributable indirect costs and carrying costs, less accumulated depreciation and any impairment. When there is a legal obligation associated with the retirement of property, a liability, when reliably estimable, is initially recognized at its fair value and a corresponding asset retirement cost is added to the gross book value of the related asset and amortized to expense over the estimated term to retirement. The Company reviews the carrying amounts of its properties whenever changes in circumstances indicate that such carrying amounts may not be recoverable based on future undiscounted cash flows. When such properties are determined to be impaired, recorded asset values are revised to their fair value and an impairment loss is recognized. The Company recognizes expenditures as additions to properties or operating expenses based on whether the expenditures increase the output or service capacity, lower the associated operating costs or extend the useful life of the properties and whether the expenditures exceed minimum physical and financial thresholds. Much of the additions to properties, both new and replacement properties, are self-constructed. These are initially recorded at cost, including direct costs and attributable indirect costs, overheads and carrying costs. Direct costs include, among other things, labour costs, purchased services, equipment costs and material costs. Attributable indirect costs and overheads include incremental long-term variable costs resulting from the execution of capital projects. Indirect costs mainly include work trains, material distribution, highway vehicles and work equipment. Overheads primarily include a portion of the engineering department’s costs, which plans, designs and administers these capital projects. These costs are allocated to projects by applying a measure consistent with the nature of the cost, based on cost studies. For replacement properties, the project costs are allocated to dismantling and installation based on cost studies. Dismantling work, which is expensed, is performed concurrently with the installation. Ballast programs including undercutting, shoulder ballasting and renewal programs that form part of the annual track program are capitalized as this work, and the related added ballast material, significantly improves drainage, which in turn extends the life of ties and other track materials. These costs are tracked separately from the underlying assets and depreciated over the period to the next estimated similar ballast program. Spot replacement of ballast is considered a repair which is expensed as incurred. The costs of large refurbishments are capitalized and locomotive overhauls are expensed as incurred, except where overhauls represent a betterment of the locomotive in which case costs are capitalized. The Company capitalizes development costs for major new computer systems. The Company follows group depreciation, which groups assets which are similar in nature and have similar economic lives. The property groups are depreciated on a straight-line basis reflecting their expected economic lives determined by depreciation studies. Depreciation studies are regular reviews of asset service lives, salvage values, accumulated depreciation and other related factors. Depreciation rates are established through these studies. Actual use and retirement of assets may vary from current estimates, and would be identified in the next study. These changes in expected economic lives would impact the amount of depreciation expense recognized in future periods. All track assets are depreciated using a straight-line method which recognizes the value of the asset consumed as a percentage of the whole life of the asset. When depreciable property is retired or otherwise disposed of in the normal course of business, the book value, less net salvage proceeds, is charged to accumulated depreciation and if different than the assumptions under the depreciation study could potentially result in adjusted depreciation expense over a period of years. However, when removal costs exceed the salvage value on assets and the Company has no legal obligation to remove the assets, the removal costs incurred are charged to income in the period in which the assets are removed and are not charged to accumulated depreciation. For certain asset classes, the historical cost of the asset is separately recorded in the Company’s property records. This amount is retired from the property records upon retirement of the asset. For assets for which the historical cost cannot be separately identified the amount of the gross book value to be retired is estimated using either an indexation methodology, whereby the current replacement cost of the asset is indexed to the estimated year of installation for the asset, or a first-in, first-out approach, or statistical analysis is used to determine the age of the retired asset. CP uses indices that closely correlate to the principal costs of the assets. There are a number of estimates inherent in the depreciation and retirement processes and as it is not possible to precisely estimate each of these variables until a group of property is completely retired, CP regularly monitors the estimated service lives of assets and the associated accumulated depreciation for each asset class to ensure depreciation rates are appropriate. If the recorded amounts of accumulated depreciation are greater or less than the amounts indicated by the depreciation studies, then the excess or deficit is amortized as a component of depreciation expense over the remaining service lives of the applicable asset classes. For the sale or retirement of larger groups of depreciable assets that are unusual and were not considered in the Company’s depreciation studies, CP records a gain or loss for the difference between net proceeds and net book value of the assets sold or retired. The accumulated depreciation to be retired includes asset-specific accumulated depreciation, when known, and an appropriate portion of the accumulated depreciation recorded for the relevant asset class as a whole, calculated using a cost-based allocation. Revisions to the estimated useful lives and net salvage projections constitute a change in accounting estimate and are addressed prospectively by amending depreciation rates. Equipment under finance lease is included in Properties and depreciated over the period of expected use.
Leases	Leases The Company has leases for rolling stock, buildings, vehicles, railway equipment, roadway machines, and information systems hardware. CP has entered into rolling stock and roadway machine leases that are fully variable or contain both fixed and variable components. Variable components are dependent on the hours and miles that the underlying equipment has been used. Fixed term, short-term, and variable operating lease costs are recorded in "Equipment rents" and "Purchased services and other" on the Company's Consolidated Statements of Income. Components of finance lease costs are recorded in "Depreciation and amortization" and "Net interest expense" on the Company's Consolidated Statements of Income. The Company determines lease existence and classification at the lease inception date. Leases are identified when an agreement conveys the right to control identified property for a period of time in exchange for consideration. The Company recognizes both an operating lease liability and right-of-use (“ROU”) asset for operating leases with fixed terms and in-substance fixed terms. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating and finance lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Lease payments include fixed and variable payments that are based on an index or a rate. If the Company's leases do not provide a readily determinable implicit interest rate, the Company uses internal incremental secured borrowing rates for comparable tenor in the same currency at the commencement date in determining the present value of lease payments. Operating and finance lease ROU assets also include lease prepayments and initial direct costs, but are reduced by lease incentives. The lease term may include periods associated with options to extend or exclude periods associated with options to terminate the lease when it is reasonably certain that the Company will exercise these options. The Company has short-term operating leases with terms of 12 months or less, some of which include options to purchase that the Company is not reasonably certain to exercise. The Company has elected to apply the recognition exemption and, as such, accounts for leases with a term of 12 months or less off-balance sheet. Therefore, lease payments on these short-term operating leases are not included in operating lease ROU assets and liabilities, but are recognized as an expense in the Company's Consolidated Statements of Income on a straight-line basis over the term of the lease. Further, the Company has elected to combine lease and non-lease components for all leases, except for leases of roadway machines and information systems hardware.
Assets held for sale	Assets held for sale Assets to be disposed that meet the held for sale criteria are reported in "Other assets" at the lower of their carrying amount and fair value, less costs to sell, and are no longer depreciated.
Goodwill and intangible assets	Goodwill and intangible assets Goodwill represents the excess of the purchase price over the fair value of identifiable net assets upon acquisition of a business. Goodwill is assigned to the reporting units that are expected to benefit from the business acquisition which, after integration of operations with the railway network, may be different than the acquired business. The carrying value of goodwill, which is not amortized, is assessed for impairment annually in the fourth quarter of each year as at October 1 st , or more frequently as economic events dictate. The Company has the option of performing an assessment of certain qualitative factors to determine if it is more likely than not that the fair value of a reporting unit is less than its carrying value or proceeding directly to a quantitative impairment test. Qualitative factors include but are not limited to, economic, market and industry conditions, cost factors and overall financial performance of the reporting unit. If the assessment of qualitative factors indicates that the carrying value is less than the fair value, then performing the quantitative goodwill impairment test is unnecessary. The quantitative assessment compares the fair value of the reporting unit to its carrying value, including goodwill. If the fair value of the reporting unit is less than its carrying value, goodwill is impaired. The impairment charge that would be recognized is the excess of the carrying value over the fair value of the reporting unit, limited to the total amount of goodwill allocated to the reporting unit. Intangible assets with finite lives are amortized on a straight-line basis over the estimated useful lives of the respective assets. Favourable leases, customer relationships and interline contracts have amortization periods ranging from 15 to 20 years. When there is a change in the estimated useful life of an intangible asset with a finite life, amortization is adjusted prospectively.
Pensions and other benefits	Pensions and other benefits Pension costs are actuarially determined using the projected-benefit method pro-rated over the credited service periods of employees. This method incorporates management’s best estimates of expected plan investment performance, salary escalation and retirement ages of employees. The expected return on fund assets is calculated using market-related asset values developed from a five-year average of market values for the fund’s public equity securities and absolute return strategies (with each prior year’s market value adjusted to the current date for assumed investment income during the intervening period) plus the market value of the fund’s fixed income, real estate, infrastructure and private debt securities, subject to the market-related asset value not being greater than 120% of the market value nor being less than 80% of the market value. The discount rate used to determine the projected-benefit obligation is based on blended market interest rates on high-quality debt instruments with matching cash flows. Unrecognized actuarial gains and losses in excess of 10% of the greater of the benefit obligation and the market-related value of plan assets are amortized over the expected average remaining service period of active employees expected to receive benefits under the plan (approximately 12 years). Prior service costs arising from collectively bargained amendments to pension plan benefit provisions are amortized over the term of the applicable union agreement. Prior service costs arising from all other sources are amortized over the expected average remaining service period of active employees who are expected to receive benefits under the plan at the date of amendment. Costs for post-retirement and post-employment benefits other than pensions, including post-retirement health care and life insurance and some workers’ compensation and long-term disability benefits in Canada, are actuarially determined on a basis similar to pension costs. The over or under funded status of defined benefit pension and other post-retirement benefit plans are measured as the difference between the fair value of the plan assets and the benefit obligation, and are recognized on the balance sheets. In addition, any unrecognized actuarial gains and losses and prior service costs and credits that arise during the period are recognized as a component of “Other comprehensive loss”, net of tax. Gains and losses on post-employment benefits that do not vest or accumulate, including some workers’ compensation and long-term disability benefits in Canada, are included immediately on the Company's Consolidated Statements of Income as "Other components of net periodic benefit cost or recovery". The current service cost component of net periodic benefit cost is reported in "Compensation and benefits" for pensions and post-retirement benefits, and in "Purchased services and other" for self-insured workers' compensation and long-term disability benefits on the Company's Consolidated Statements of Income. Other components of net periodic benefit cost or recovery are reported in "Other components of net periodic benefit cost or recovery" outside of Operating income on the Company's Consolidated Statements of Income. Capitalization of pension costs, when applicable, is restricted to the current service cost component of net periodic benefit cost.
Financial instruments	Financial instruments Financial instruments are contracts that give rise to a financial asset of one party and a financial liability or equity instrument of another party. Financial instruments are recognized initially at fair value, which is the amount of consideration that would be agreed upon in an arm’s-length transaction between willing parties. Subsequent measurement depends on how the financial instruments have been classified. Accounts receivable and other investments, classified as loans and receivables, are measured at amortized cost, using the effective interest method. Cash and cash equivalents and derivatives are classified as held for trading and are measured at fair value. Accounts payable, accrued liabilities, short-term borrowings, other long-term liabilities, and long-term debt are also measured at amortized cost.
Derivative financial instruments	Derivative financial instruments Derivative financial and commodity instruments may be used from time to time by the Company to manage its exposure to risks relating to foreign currency exchange rates, stock-based compensation, interest rates, and fuel prices. When CP utilizes derivative instruments in hedging relationships, CP identifies, designates, and documents those hedging transactions and regularly tests the transactions to demonstrate effectiveness in order to continue hedge accounting. All derivative instruments are classified as held for trading and recorded at fair value. Any change in the fair value of derivatives that are not designated as hedges is recognized in the period in which the change occurs in the Company's Consolidated Statements of Income in the line item to which the derivative instrument is related. For fair value hedges, the periodic changes in value are recognized in income, on the same line as the changes in value of the hedged items are also recorded. For an effective cash flow hedge, the entire change in value of the hedging instrument is recognized in “Other comprehensive loss”. The change in value of the effective cash flow hedge remains in “Accumulated other comprehensive loss” until the related hedged item settles, at which time amounts recognized in “Accumulated other comprehensive loss” are reclassified to the same income or balance sheet account that records the hedged item.
Environmental remediation	Environmental remediation Environmental remediation accruals, recorded on an undiscounted basis unless a reliably determinable estimate as to amount and timing of costs can be established, cover site-specific remediation programs. The accruals are recorded when the costs to remediate are probable and reasonably estimable. Certain future costs to monitor sites are discounted at an adjusted risk-free rate. Provisions for environmental remediation costs are recorded in “Other long-term liabilities”, except for the current portion, which is recorded in “Accounts payable and accrued liabilities”.
Stock-based compensation	Stock-based compensation CP follows the fair value based approach to account for stock options. Compensation expense and an increase in “Additional paid-in capital” are recognized for stock options over their vesting period or over the period from the grant date to the date employees become eligible to retire, when this is shorter than the vesting period, based on their fair values on the grant date as determined using the Black-Scholes option-pricing model. Forfeitures are estimated at issuance and monitored on a periodic basis. Any consideration paid by employees on exercise of stock options is credited to “Share capital” when the option is exercised and the recorded fair value of the option is removed from “Additional paid-in capital" and credited to “Share capital”. Compensation expense is also recognized for performance share units (“PSUs”), performance deferred share units ("PDSUs"), deferred share units ("DSUs"), and restricted share units (“RSUs”) that settle in cash using the fair value method. Compensation expense is recognized over the vesting period or over the period from the grant date to the date employees become eligible to retire, when this is shorter than the vesting period where applicable. Forfeitures are estimated at issuance and monitored on a periodic basis. The employee share purchase plan gives rise to compensation expense that is recognized using the issue price by amortizing the cost over the vesting period.

Accounting Changes (Policies)

Accounting Changes (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Changes	Implemented in 2020 Financial Instruments - Credit Losses On January 1, 2020, the Company adopted the new Accounting Standards Update ("ASU") 2016-13, issued by the Financial Accounting Standards Board ("FASB"), and all related amendments under FASB Accounting Standards Codification ("ASC") Topic 326, Financial Instruments - Credit Losses. Using a modified retrospective approach, the Company recognized a cumulative-effect adjustment to its opening retained earnings balance in the period of adoption. Accordingly, comparative financial information has not been restated and continues to be reported under the accounting standards in effect for those periods. The impact of the adoption of ASC 326 as at January 1, 2020 was an increase in the allowance for credit losses of $1 million, with the offsets to "Deferred income taxes" and "Retained earnings" on the Company's Consolidated Balance Sheet. See Note 9 for further discussion of the current period credit loss. Simplification of Financial Disclosures about Guarantors During the second quarter of 2020, the Company early adopted the Securities and Exchange Commission amendments to the financial disclosure requirements for guarantors and issuers of guaranteed securities, as specified in Rule 3-10 of Regulation S-X. The amendments simplify disclosure requirements by replacing condensed consolidating financial information (“CCFI”) with summarized financial information and expanded qualitative non-financial disclosures about the guarantees, issuers, and guarantors. This disclosure can be found in Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations, Liquidity and Capital Resources.

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table disaggregates the Company’s revenues from contracts with customers by major source: (in millions of Canadian dollars) 2020 2019 2018 Freight Grain $ 1,829 $ 1,684 $ 1,566 Coal 566 682 673 Potash 493 462 486 Fertilizers and sulphur 290 250 243 Forest products 328 304 284 Energy, chemicals and plastics 1,519 1,534 1,243 Metals, minerals and consumer products 629 752 797 Automotive 324 352 322 Intermodal 1,563 1,593 1,538 Total freight revenues 7,541 7,613 7,152 Non-freight excluding leasing revenues 107 116 102 Revenues from contracts with customers 7,648 7,729 7,254 Leasing revenues 62 63 62 Total revenues $ 7,710 $ 7,792 $ 7,316
Changes in Contract Liabilities	The following table summarizes the changes in contract liabilities for the years ended December 31, 2020 and 2019: (in millions of Canadian dollars) 2020 2019 Opening balance $ 146 $ 2 Revenue recognized that was included in the contract liability balance at the beginning of the period (100) (2) Increase due to consideration received, net of revenue recognized during the period 15 146 Closing balance $ 61 $ 146

Other Expense (Income) (Tables)

Other Expense (Income) (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other (income) expense	(in millions of Canadian dollars) 2020 2019 2018 Foreign exchange (gain) loss on debt and lease liabilities $ (14) $ (94) $ 168 Other foreign exchange (gains) losses (1) (4) 3 Other 8 9 3 Other (income) expense $ (7) $ (89) $ 174

Net Interest Expense (Tables)

Net Interest Expense (Tables)	12 Months Ended
	Dec. 31, 2020
Interest Income (Expense), Net [Abstract]
Net Interest Expense	(in millions of Canadian dollars) 2020 2019 2018 Interest cost $ 478 $ 471 $ 475 Interest capitalized to Properties (16) (17) (20) Interest expense 462 454 455 Interest income (4) (6) (2) Net interest expense $ 458 $ 448 $ 453

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of the Major Components of the Company's Income Tax Expense	The following is a summary of the major components of the Company’s income tax expense: (in millions of Canadian dollars) 2020 2019 2018 Current income tax expense $ 537 $ 525 $ 381 Deferred income tax expense Origination and reversal of temporary differences 277 316 214 Effect of tax rate decrease (32) (95) (21) Effect of hedge of net investment in foreign subsidiaries (18) (38) 64 Other (6) (2) (1) Total deferred income tax expense 221 181 256 Total income taxes $ 758 $ 706 $ 637 Income before income tax expense Canada $ 2,518 $ 2,392 $ 1,788 Foreign 684 754 800 Total income before income tax expense $ 3,202 $ 3,146 $ 2,588 Income tax expense Current Canada $ 412 $ 410 $ 336 Foreign 125 115 45 Total current income tax expense 537 525 381 Deferred Canada 231 141 174 Foreign (10) 40 82 Total deferred income tax expense 221 181 256 Total income taxes $ 758 $ 706 $ 637
Deferred Income Tax Assets and Liabilities	The items comprising the deferred income tax assets and liabilities are as follows: (in millions of Canadian dollars) 2020 2019 Deferred income tax assets Amount related to tax losses carried forward $ 17 $ 6 Liabilities carrying value in excess of tax basis 131 139 Unrealized foreign exchange losses 4 26 Environmental remediation costs 22 22 Other 4 4 Total net deferred income tax assets 178 197 Deferred income tax liabilities Properties carrying value in excess of tax basis 3,708 3,524 Pensions carrying value in excess of tax basis 43 83 Other 93 91 Total deferred income tax liabilities 3,844 3,698 Total net deferred income tax liabilities $ 3,666 $ 3,501
Expected Income Tax Expense Reconciled To Income Tax Expense	Expected income tax expense at statutory rates is reconciled to income tax expense as follows: (in millions of Canadian dollars, except percentage) 2020 2019 2018 Statutory federal and provincial income tax rate (Canada) 26.31 % 26.77 % 26.86 % Expected income tax expense at Canadian enacted statutory tax rates $ 842 $ 842 $ 695 (Decrease) increase in taxes resulting from: (Gains) losses not subject to tax (23) (19) 8 Canadian tax rate differentials (3) — — Foreign tax rate differentials (32) (33) (55) Effect of tax rate decrease (32) (95) (21) Valuation allowance — (5) 5 Unrecognized tax benefits (7) 33 — Other 13 (17) 5 Income tax expense $ 758 $ 706 $ 637
Reconciliation of Uncertain Tax Positions In Relation To Unrecognized Tax Benefits	The following table provides a reconciliation of uncertain tax positions in relation to unrecognized tax benefits for Canada and the U.S. for the year ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Unrecognized tax benefits at January 1 $ 52 $ 13 $ 13 Increase in unrecognized: Tax benefits related to the current year — 9 1 Tax benefits related to prior years 10 34 — Dispositions: Gross uncertain tax benefits related to prior years (9) — (1) Settlements with taxing authorities 2 (4) — Unrecognized tax benefits at December 31 $ 55 $ 52 $ 13

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Number Of Shares Used In the Earnings Per Share Calculations	The number of shares used in the earnings per share calculations are reconciled as follows: (in millions of Canadian dollars, except per share data) 2020 2019 2018 Net income $ 2,444 $ 2,440 $ 1,951 Weighted-average basic shares outstanding (millions) 135.5 138.8 142.9 Dilutive effect of stock options (millions) 0.5 0.5 0.4 Weighted-average diluted shares outstanding (millions) 136.0 139.3 143.3 Earnings per share – basic $ 18.05 $ 17.58 $ 13.65 Earnings per share – diluted $ 17.97 $ 17.52 $ 13.61

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2020
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Other comprehensive (loss) income and related tax effects	The components of Other comprehensive loss and the related tax effects are as follows: (in millions of Canadian dollars) Before Income tax (expense) recovery Net of tax For the year ended December 31, 2020 Unrealized foreign exchange (loss) gain on: Translation of the net investment in U.S. subsidiaries $ (118) $ — $ (118) Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) 136 (18) 118 Realized loss on derivatives designated as cash flow hedges recognized in income 9 (3) 6 Change in pension and other benefits actuarial gains and losses (403) 108 (295) Change in prior service pension and other benefit costs (4) 1 (3) Other comprehensive loss $ (380) $ 88 $ (292) For the year ended December 31, 2019 Unrealized foreign exchange (loss) gain on: Translation of the net investment in U.S. subsidiaries $ (251) $ — $ (251) Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) 288 (38) 250 Realized loss on derivatives designated as cash flow hedges recognized in income 10 (2) 8 Change in pension and other benefits actuarial gains and losses (661) 175 (486) Other comprehensive loss $ (614) $ 135 $ (479) For the year ended December 31, 2018 Unrealized foreign exchange gain (loss) on: Translation of the net investment in U.S. subsidiaries $ 419 $ — $ 419 Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (Note 17) (479) 64 (415) Change in derivatives designated as cash flow hedges: Realized loss on cash flow hedges recognized in income 10 (3) 7 Unrealized gain on cash flow hedges and other 28 (8) 20 Change in pension and other benefits actuarial gains and losses (447) 115 (332) Change in prior service pension and other benefit costs (2) 1 (1) Other comprehensive loss $ (471) $ 169 $ (302)
Accumulated other comprehensive loss, Net of tax	The components of Accumulated other comprehensive loss, net of tax, are as follows: (in millions of Canadian dollars) 2020 2019 Unrealized foreign exchange gain on translation of the net investment in U.S. subsidiaries $ 493 $ 611 Unrealized foreign exchange loss on translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries (381) (499) Net deferred losses on derivatives and other (48) (54) Amounts for defined benefit pension and other post-retirement plans not recognized in income (Note 22) (2,878) (2,580) Accumulated other comprehensive loss $ (2,814) $ (2,522)
Changes in Accumulated other comprehensive loss by component	Changes in Accumulated other comprehensive loss by component are as follows: (in millions of Canadian dollars) Foreign currency (1) Derivatives and (1) Pension and post- (1) Total (1) Opening balance, January 1, 2020 $ 112 $ (54) $ (2,580) $ (2,522) Other comprehensive loss before reclassifications — (2) (430) (432) Amounts reclassified from accumulated other comprehensive loss — 8 132 140 Net other comprehensive income (loss) — 6 (298) (292) Closing balance, December 31, 2020 $ 112 $ (48) $ (2,878) $ (2,814) Opening balance, January 1, 2019 $ 113 $ (62) $ (2,094) $ (2,043) Other comprehensive loss before reclassifications (1) — (550) (551) Amounts reclassified from accumulated other comprehensive loss — 8 64 72 Net other comprehensive (loss) income (1) 8 (486) (479) Closing balance, December 31, 2019 $ 112 $ (54) $ (2,580) $ (2,522) (1) Amounts are presented net of tax.
Amounts in Pension and Post-retirement Defined Benefit Plans Reclassified from AOCL	Amounts in Pension and post-retirement defined benefit plans reclassified from Accumulated other comprehensive loss are as follows: (in millions of Canadian dollars) 2020 2019 Amortization of prior service costs (1) $ (1) $ — Recognition of net actuarial loss (1) 180 84 Total before income tax 179 84 Income tax recovery (47) (20) Total net of income tax $ 132 $ 64 (1) Impacts "Other components of net periodic benefit recovery" on the Consolidated Statements of Income.

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Schedule of Accounts Receivable, Net	As at December 31, 2020 As at December 31, 2019 (1) (in millions of Canadian dollars) Freight Non-Freight Total Freight Non-Freight Total Total accounts receivable $ 662 $ 203 $ 865 $ 637 $ 210 $ 847 Allowance for credit losses (25) (15) (40) (26) (16) (42) Total accounts receivable, net $ 637 $ 188 $ 825 $ 611 $ 194 $ 805 (1) Prior year amounts have not been adjusted under the modified retrospective method (Note 2).
Accounts Receivable, Allowance for Credit Loss	For the twelve months ended December 31, 2020 (in millions of Canadian dollars) Freight Non-Freight Total Allowance for credit losses, opening balance (1) $ (27) $ (16) $ (43) Current period credit loss provision, net 2 1 3 Allowance for credit losses, closing balance $ (25) $ (15) $ (40) (1) Opening balance at January 1, 2020 was restated as described in Note 2.

Business combination (Tables)

Business combination (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Schedule of Fair Values of Acquired Assets and Liabilities (DRTP)	The following summarizes the estimated fair values of the acquired assets and liabilities of DRTP: (in millions of Canadian dollars) December 22, 2020 Fair value of net assets acquired: Accounts receivable, net $ 5 Properties 436 Intangible assets (Note 13) 4 Accounts payable and accrued liabilities (1) Deferred taxes (55) Total identifiable assets and liabilities $ 389 Goodwill (Note 13) 90 $ 479 Consideration: Cash, net of cash acquired $ 398 Fair value of previously held equity method investment 81 Total consideration $ 479
Schedule of Fair Values of Acquired Assets and Liabilities (CMQ U.S.)	After a measurement period adjustment of $1 million to increase Other long-term liabilities and goodwill resulting from the finalization of acquisition date deferred tax, the final allocation of total consideration to the fair values of the acquired assets and liabilities of CMQ U.S. is summarized as follows: (in millions of Canadian dollars) June 3, 2020 Fair value of net assets acquired: Cash and cash equivalents $ 22 Accounts receivable, net 2 Properties 54 Intangible assets (Note 13) 27 Accounts payable and accrued liabilities (13) Other long-term liabilities (6) Total identifiable assets and liabilities $ 86 Goodwill (Note 13) 52 $ 138 Consideration: Fair value of previously held equity method investment $ 138
Schedule of Fair Values of Acquired Assets and Liabilities (CMQ Canada)	The final purchase price and allocation of the total consideration to the fair values of assets and liabilities acquired for CMQ Canada is summarized as follows: (in millions of Canadian dollars) December 30, 2019 Fair value of net assets acquired: Accounts receivable, net $ 7 Properties 42 Intangible assets (Note 13) 5 Accounts payable and accrued liabilities (2) Long-term debt maturing within one year (Note 16) (11) Other long-term liabilities (4) Total identifiable assets and liabilities 37 Goodwill (Note 13) 10 $ 47 Consideration: Cash, net of cash acquired $ 47

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investments	(in millions of Canadian dollars) 2020 2019 Investment in CMQ U.S. accounted for on an equity basis (Note 10) $ — $ 127 Other rail investments accounted for on an equity basis 150 166 Other investments 49 48 Total investments $ 199 $ 341

Properties (Tables)

Properties (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Properties	2020 2020 2019 (in millions of Canadian dollars except percentages) Weighted-average annual depreciation rate Cost Accumulated Net book Cost Accumulated Net book Track and roadway 2.8 % $ 20,676 $ 5,859 $ 14,817 $ 19,299 $ 5,522 $ 13,777 Buildings 2.9 % 937 259 678 833 237 596 Rolling stock 2.8 % 4,702 1,498 3,204 4,529 1,445 3,084 Information systems software (1) 9.3 % 569 253 316 527 215 312 Other 5.2 % 2,167 760 1,407 2,067 680 1,387 Total $ 29,051 $ 8,629 $ 20,422 $ 27,255 $ 8,099 $ 19,156 (1) During 2020, CP capitalized costs attributable to the design and development of internal-use software in the amount of $45 million (2019 – $55 million; 2018 – $53 million). Current year depreciation expense related to internal use software was $42 million (2019 – $44 million; 2018 – $49 million).
Finance Leases Included In Properties	Finance leases included in properties 2020 2019 (in millions of Canadian dollars) Cost Accumulated Net book Cost Accumulated Net book Rolling stock 302 138 164 303 130 173 Other 8 1 7 4 — 4 Total assets held under finance lease $ 310 $ 139 $ 171 $ 307 $ 130 $ 177

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill Intangible assets (in millions of Canadian dollars) Net Cost Accumulated Net Total goodwill and intangible assets Balance at December 31, 2018 $ 194 $ 22 $ (14) $ 8 $ 202 Additions (Note 10) 10 5 — 5 15 Amortization — — (1) (1) (1) Foreign exchange impact (10) — — — (10) Balance at December 31, 2019 194 27 (15) 12 206 Additions (Note 10) 142 31 — 31 173 Amortization — — (3) (3) (3) Foreign exchange impact (7) (3) — (3) (10) Balance at December 31, 2020 $ 329 $ 55 $ (18) $ 37 $ 366

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	(in millions of Canadian dollars) 2020 2019 Operating lease ROU assets (Note 19) $ 316 $ 358 Contracted customer incentives 60 32 Long-term materials 37 41 Other 25 20 Total other assets $ 438 $ 451

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities	(in millions of Canadian dollars) 2020 2019 Trade payables $ 401 $ 453 Accrued charges 294 348 Accrued interest 134 131 Dividends payable 127 114 Stock-based compensation liabilities 121 85 Income and other taxes payable 115 139 Payroll-related accruals 68 78 Operating lease liabilities (Note 19) 63 69 Accrued vacation 59 60 Personal injury and other claims provision 37 55 Deferred revenue (Note 3) 27 142 Deferred real estate lease and license revenue (1) 11 10 Provision for environmental remediation (Note 18) 9 7 Other (1) 1 2 Total accounts payable and accrued liabilities $ 1,467 $ 1,693 (1) 2019 comparative figures have been reclassified to conform with current presentation.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Components of Long-term Debt	The following table outlines the Company's outstanding long-term debt as at December 31, 2020: (in millions of Canadian dollars except percentages) Maturity Currency 2020 2019 9.450% 30-year Debentures (A) Aug 2021 U.S.$ 318 325 5.100% 10-year Medium Term Notes (A) Jan 2022 CDN$ 125 125 4.500% 10-year Notes (A) Jan 2022 U.S.$ 318 324 4.450% 12.5-year Notes (A) Mar 2023 U.S.$ 445 454 2.900% 10-year Notes (A) Feb 2025 U.S.$ 891 909 3.700% 10.5-year Notes (A) Feb 2026 U.S.$ 318 324 4.000% 10-year Notes (A) Jun 2028 U.S.$ 636 649 3.150% 10-year Notes (A) Mar 2029 CDN$ 399 399 2.050% 10-year Notes (A) Mar 2030 U.S.$ 636 — 7.125% 30-year Debentures (A) Oct 2031 U.S.$ 446 454 5.750% 30-year Debentures (A) Mar 2033 U.S.$ 312 318 4.800% 20-year Notes (A) Sep 2035 U.S.$ 381 388 5.950% 30-year Notes (A) May 2037 U.S.$ 567 578 6.450% 30-year Notes (A) Nov 2039 CDN$ 400 400 5.750% 30-year Notes (A) Jan 2042 U.S.$ 313 319 4.800% 30-year Notes (A) Aug 2045 U.S.$ 698 712 3.050% 30-year Notes (A) Mar 2050 CDN$ 298 — 6.125% 100-year Notes (A) Sep 2115 U.S.$ 1,146 1,169 8.000% 5-year Promissory Notes (B) up to Jun 2020 U.S.$ — 11 5.41% Senior Secured Notes (C) Mar 2024 U.S.$ 89 100 6.91% Secured Equipment Notes (D) Oct 2024 CDN$ 75 91 7.49% Equipment Trust Certificates (E) Jan 2021 U.S.$ 14 55 Obligations under finance leases 1.99% -2.97% (F) 2021 - 2023 CDN$/U.S.$ 4 3 6.99% (F) Mar 2022 U.S.$ 97 99 6.57% (F) Dec 2026 U.S.$ 38 45 12.77% (F) Jan 2031 CDN$ 4 4 Commercial Paper up to Feb 2021 U.S.$ 820 516 9,788 8,771 Perpetual 4% Consolidated Debenture Stock (G) U.S.$ 39 39 Perpetual 4% Consolidated Debenture Stock (G) G.B.£ 6 6 9,833 8,816 Unamortized fees on long-term debt (62) (59) 9,771 8,757 Less: Long-term debt maturing within one year 1,186 599 $ 8,585 $ 8,158

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	(in millions of Canadian dollars) 2020 2019 Operating lease liabilities, net of current portion (Note 19) $ 248 $ 285 Stock-based compensation liabilities, net of current portion 146 111 Provision for environmental remediation, net of current portion (1) 71 70 Deferred revenue, net of current portion (Note 3) (2) 34 4 Deferred real estate lease and license revenue, net of current portion (3) 18 20 Deferred gains on sale leaseback transactions (3) 5 6 Other, net of current portion (2) 63 66 Total other long-term liabilities $ 585 $ 562 (1) As at December 31, 2020, the aggregate provision for environmental remediation, including the current portion was $80 million (2019 – $77 million). (2) 2019 comparative figures have been reclassified to conform with current presentation. (3) The deferred real estate lease and license revenue and deferred gains on sale leaseback transactions are being amortized to income on a straight-line basis over the related lease terms.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Components of Lease Expense	Components of lease expense for the year ended December 31 are as follows: (in millions of Canadian dollars) 2020 2019 Operating lease cost $ 83 $ 89 Short-term lease cost 10 10 Variable lease cost 13 13 Sublease income (3) (3) Finance Lease Cost Amortization of right-of-use assets 9 9 Interest on lease liabilities 11 11 Total lease costs $ 123 $ 129
Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases is as follows: (in millions of Canadian dollars) Classification 2020 2019 Assets Operating Other assets $ 316 $ 358 Finance Properties, net book value 171 177 Liabilities Current Operating Accounts payable and accrued liabilities 63 69 Finance Long-term debt maturing within one year 8 7 Long-term Operating Other long-term liabilities 248 285 Finance Long-term debt 135 144
Weighted Average Remaining Lease Terms and Discount Rates	The following table provides the Company's weighted-average remaining lease terms and discount rates: 2020 2019 Weighted-Average Remaining Lease Term Operating leases 7 years 7 years Finance leases 3 years 4 years Weighted-Average Discount Rate Operating leases 3.32 % 3.45 % Finance leases 7.06 % 7.07 %
Supplemental Information Related to Leases	Supplemental information related to leases is as follows: (in millions of Canadian dollars) 2020 2019 Cash paid for amounts included in measurement of lease liabilities Operating cash outflows from operating leases $ 74 $ 82 Operating cash outflows from finance leases 10 10 Financing cash outflows from finance leases 8 6 Right-of-use assets obtained in exchange for lease liabilities Operating leases 34 38 Finance leases 4 4
Maturities of Lease Liabilities	The following table provides the maturities of lease liabilities for the next five years and thereafter as at December 31, 2020: (in millions of Canadian dollars) Finance Leases Operating Leases 2021 $ 11 $ 71 2022 107 59 2023 9 53 2024 8 42 2025 8 34 Thereafter 12 88 Total lease payments 155 347 Imputed interest (12) (36) Present value of lease payments $ 143 $ 311

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Summary of Information Related to Common Share Balances	The following table summarizes information related to Common Share balances as at December 31: (number of shares in millions) 2020 2019 2018 Share capital, January 1 137.0 140.5 144.9 CP Common Shares repurchased (4.0) (3.8) (4.6) Shares issued under stock option plan 0.3 0.3 0.2 Share capital, December 31 133.3 137.0 140.5
Activities Under the Share Repurchase Programs	The following table provides activities under the share repurchase programs for each of the years ended December 31: 2020 2019 2018 Number of Common Shares repurchased (1) 3,973,076 3,794,149 4,683,162 Weighted-average price per share (2) $ 371.74 $ 300.65 $ 240.68 Amount of repurchase (in millions) (2) $ 1,477 $ 1,141 $ 1,127 (1) Includes shares repurchased but not yet cancelled at year end. (2) Includes brokerage fees.

Change in Non-Cash Working Ca_2

Change in Non-Cash Working Capital Balances Related to Operations (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Changes In Non-cash Working Capital Balances Related To Operations	(in millions of Canadian dollars) 2020 2019 2018 (Use) source of cash: Accounts receivable, net $ (61) $ 27 $ (107) Materials and supplies (15) (8) (11) Other current assets (5) (24) 30 Accounts payable and accrued liabilities (308) (21) 153 Change in non-cash working capital $ (389) $ (26) $ 65

Pensions and Other Benefits (Ta

Pensions and Other Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Net Periodic Benefit Cost	The elements of net periodic benefit cost for DB pension plans and other benefits recognized in the year include the following components: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2018 2020 2019 2018 Current service cost (benefits earned by employees) $ 140 $ 107 $ 120 $ 12 $ 11 $ 12 Other components of net periodic benefit cost (recovery): Interest cost on benefit obligation 406 450 438 17 20 19 Expected return on fund assets (945) (947) (955) — — — Recognized net actuarial loss 177 84 114 4 12 2 Amortization of prior service costs (1) (1) (2) — 1 — Total other components of net periodic benefit (recovery) cost (363) (414) (405) 21 33 21 Net periodic benefit (recovery) cost $ (223) $ (307) $ (285) $ 33 $ 44 $ 33
Schedule of Changes in Projected Benefit Obligation	Information about the Company’s DB pension plans and other benefits, in aggregate, is as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Change in projected benefit obligation: Benefit obligation at January 1 $ 12,610 $ 11,372 $ 541 $ 501 Current service cost 140 107 12 11 Interest cost 406 450 17 20 Employee contributions 42 41 — — Benefits paid (653) (646) (34) (34) Foreign currency changes (5) (10) — — Plan amendments and other 3 — — — Actuarial loss 1,256 1,296 17 43 Projected benefit obligation at December 31 $ 13,799 $ 12,610 $ 553 $ 541 The net actuarial losses for Pensions and Other benefits in 2020 were primarily due to the decrease in discount rate from 3.25% to 2.58%. The net actuarial losses for Pensions and Other benefits in 2019 were primarily due to the decrease in discount rate from 4.01% to 3.25%.
Schedule of Changes in Fund Assets	Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Change in fund assets: Fair value of fund assets at January 1 $ 13,319 $ 12,349 $ 5 $ 4 Actual return on fund assets 1,634 1,528 — 1 Employer contributions 27 53 34 34 Employee contributions 42 41 — — Benefits paid (653) (646) (34) (34) Foreign currency changes (4) (6) — — Fair value of fund assets at December 31 $ 14,365 $ 13,319 $ 5 $ 5 Funded status – plan surplus (deficit) $ 566 $ 709 $ (548) $ (536)
Funded Status of Pension Plans	The table below shows the aggregate pension projected benefit obligation and aggregate fair value of plan assets for pension plans with fair value of plan assets in excess of projected benefit obligations (i.e. surplus), and for pension plans with projected benefit obligations in excess of fair value of plan assets (i.e. deficit): 2020 2019 (in millions of Canadian dollars) Pension Pension Pension Pension Projected benefit obligation at December 31 $ (13,220) $ (579) $ (12,076) $ (534) Fair value of fund assets at December 31 14,114 251 13,079 240 Funded Status $ 894 $ (328) $ 1,003 $ (294)
Pension Asset and Liabilities in the Company's Consolidated Balance Sheets	Amounts recognized in the Company’s Consolidated Balance Sheets are as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Pension asset $ 894 $ 1,003 $ — $ — Accounts payable and accrued liabilities (11) (11) (33) (34) Pension and other benefit liabilities (317) (283) (515) (502) Total amount recognized $ 566 $ 709 $ (548) $ (536)
Accumulated Other Comprehensive Loss	Amounts recognized in accumulated other comprehensive loss are as follows: Pensions Other benefits (in millions of Canadian dollars) 2020 2019 2020 2019 Net actuarial loss: Other than deferred investment gains $ 3,960 $ 3,434 $ 104 $ 91 Deferred investment gains (95) 41 — — Prior service cost 5 1 1 1 Deferred income tax (1,070) (964) (27) (24) Total (Note 8) $ 2,800 $ 2,512 $ 78 $ 68
Actuarial Assumptions	Weighted-average actuarial assumptions used were approximately: (percentages) 2020 2019 2018 Benefit obligation at December 31: Discount rate 2.58 3.25 4.01 Projected future salary increases 2.75 2.75 2.75 Health care cost trend rate 5.00 (1) 5.50 (1) 6.00 (1) Benefit cost for year ended December 31: Discount rate 3.25 4.01 3.80 Expected rate of return on fund assets (3) 7.25 7.50 7.75 Projected future salary increases 2.75 2.75 2.75 Health care cost trend rate 5.50 (1) 6.00 (1) 7.00 (2) (1) The health care cost trend rate was assumed to be 6.00% in 2019 and 5.50% in 2020 and is assumed to be 5.00% per year in 2021 and thereafter. (2) The health care cost trend rate was previously assumed to be 7.00% in 2018, and then decreasing by 0.50% per year to an ultimate rate of 5.00% per year in 2022 and thereafter. (3) The expected rate of return on fund assets that will be used to compute the 2021 net periodic benefit credit is 6.90%.
Pension Plan Asset Allocation and Weighted-average Policy Ranges	The Company’s pension plan asset allocation, the weighted-average asset allocation targets, and the weighted average policy range for each major asset class at year end were as follows: Percentage of plan assets Asset allocation (percentage) Asset allocation target Policy range 2020 2019 Cash and cash equivalents 1.2 0 – 10 2.0 0.9 Fixed income 24.1 20 – 40 28.1 24.6 Public equity 45.1 35 – 55 49.3 54.5 Real estate and infrastructure 9.8 4 – 13 6.3 6.8 Private debt 9.8 4 – 13 3.3 2.4 Absolute return 10.0 4 – 13 11.0 10.8 Total 100.0 100.0 100.0
Summary of the Assets of the Company's DB Pension Plans	The following is a summary of the assets of the Company’s DB pension plans at December 31, 2020 and 2019. As of December 31, 2020 and 2019, there were no plan assets classified as Level 3 valued investments. Assets Measured at Fair Value Investments measured at NAV (1) Total Plan (in millions of Canadian dollars) Quoted prices in Significant other observable inputs (Level 2) December 31, 2020 Cash and cash equivalents $ 219 $ — $ — $ 219 Fixed income Government bonds (2) 284 1,699 — 1,983 Corporate bonds (2) 691 1,144 — 1,835 Mortgages (3) 220 5 — 225 Public equities Canada 1,183 — — 1,183 U.S. and international 5,871 28 — 5,899 Real estate (4) — — 704 704 Infrastructure (5) — — 199 199 Private debt (6) — — 465 465 Derivative instruments (7) — 71 — 71 Absolute return (8) Funds of hedge funds — — 1,560 1,560 Multi-strategy funds — — 22 22 $ 8,468 $ 2,947 $ 2,950 $ 14,365 December 31, 2019 Cash and cash equivalents $ 112 $ — $ — $ 112 Fixed income Government bonds (2) 233 1,857 — 2,090 Corporate bonds (2) 273 819 — 1,092 Mortgages (3) 159 5 — 164 Public equities Canada 1,351 — — 1,351 U.S. and international 5,883 22 — 5,905 Real estate (4) — — 724 724 Infrastructure (5) — — 187 187 Private debt (6) — — 313 313 Derivative instruments (7) — (59) — (59) Absolute return (8) Funds of hedge funds — — 1,418 1,418 Multi-strategy funds — — 22 22 $ 8,011 $ 2,644 $ 2,664 $ 13,319 (1) Investments measured at net asset value ("NAV"): Amounts are comprised of certain investments measured using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. (2) Government & Corporate Bonds: Fair values for bonds are based on market prices supplied by independent sources as of the last trading day. (3) Mortgages: The fair values of mortgages are based on current market yields of financial instruments of similar maturity, coupon and risk factors. (4) Real estate: Real estate fund values are based on the NAV of the funds that invest directly in real estate investments. The values of the investments have been estimated using the capital accounts representing the plan’s ownership interest in the funds. Of the total, $580 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $606 million). The remaining $124 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying real estate investments (2019 – $118 million). As at December 31, 2020, there are $32 million of unfunded commitments for real estate investments (December 31, 2019 – $35 million). (5) Infrastructure: Infrastructure fund values are based on the NAV of the funds that invest directly in infrastructure investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $112 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $119 million). The remaining $87 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying infrastructure investments (2019 – $68 million). As at December 31, 2020, there are $491 million of unfunded commitments for infrastructure investments (December 31, 2019 – $286 million). (6) Private debt: Private debt fund values are based on the NAV of the funds that invest directly in private debt investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $154 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $154 million). The remaining $311 million is not subject to redemption and is normally returned through distributions as a result of the repayment of the underlying loans (2019 - $159 million). As at December 31, 2020, there are $533 million of unfunded commitments for private debt investments (December 31, 2019 – $392 million). (7) Derivatives: The investment managers may utilize the following derivative instruments: equity futures to replicate equity index returns (Level 2); currency forwards to partially hedge foreign currency exposures (Level 2); bond forwards to reduce asset/liability interest rate risk exposures (Level 2); interest rate swaps to manage duration and interest rate risk (Level 2); credit default swaps to manage credit risk (Level 2); and options to manage interest rate risk and volatility (Level 2). The Company may utilize derivatives directly, but only for the purpose of hedging foreign currency exposures. As at December 31, 2020, there are currency forwards with a notional value of $1,041 million (December 31, 2019 – $334 million) and a fair value of $73 million (December 31, 2019 – $13 million). The fixed income investment manager utilizes a portfolio of bond forwards for the purpose of reducing asset/liability interest rate exposure. As at December 31, 2020, there are bond forwards with a notional value of $3,540 million ( December 31, 2019 – $3,269 million) and a negative fair value of $2 million (December 31, 2019 – $(72) million). (8) Absolute return: The value of absolute return fund investments is based on the NAV reported by the fund administrators. The funds have different redemption policies with redemption notice periods varying from 60 to 95 days and frequencies ranging from monthly to triennially.
Estimated Future Benefit Payments	The estimated future DB pension and other benefit payments to be paid by the plans for each of the next five years and the subsequent five-year period are as follows: (in millions of Canadian dollars) Pensions Other benefits 2021 $ 632 $ 33 2022 629 31 2023 631 31 2024 633 30 2025 635 30 2026-2030 3,203 142

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Stock Option Plan	The following table summarizes the Company’s stock option plan as at December 31, 2020: Options outstanding Non-vested options Number of Weighted-average Number of Weighted-average Outstanding, January 1, 2020 1,416,346 $ 199.12 761,784 $ 53.54 Granted 217,240 $ 344.04 217,240 $ 69.00 Exercised (232,034) $ 162.87 N/A N/A Vested N/A N/A (188,108) $ 50.91 Forfeited (13,839) $ 271.75 (13,839) $ 58.29 Expired (347) $ 168.84 N/A N/A Outstanding, December 31, 2020 1,387,366 $ 225.20 777,077 $ 58.40 Vested or expected to vest at December 31, 2020 (1) 1,366,649 $ 223.98 N/A N/A Exercisable, December 31, 2020 610,289 $ 177.65 N/A N/A (1) As at December 31, 2020, the weighted-average remaining term of vested or expected to vest options was 4.5 years with an aggregate intrinsic value of $297 million .
Stock Options Outstanding and Exercisable	The following table provides the number of stock options outstanding and exercisable as at December 31, 2020 by range of exercise price and their related intrinsic aggregate value, and for options outstanding, the weighted-average years to expiration. The table also provides the aggregate intrinsic value for in-the-money stock options, which represents the amount that would have been received by option holders had they exercised their options on December 31, 2020 at the Company’s closing stock price of $441.53. Options outstanding Options exercisable Range of exercise prices Number of Weighted-average Weighted-average Aggregate Number of Weighted-average Aggregate $65.06 - $188.78 342,773 3.4 $ 141.26 $ 103 342,773 $ 141.26 $ 103 $188.79 - $214.58 327,811 3.1 $ 196.82 $ 80 109,375 $ 203.83 $ 26 $214.59 - $261.88 394,953 4.4 $ 244.17 $ 78 134,845 $ 232.54 $ 28 $261.89 - $411.37 321,829 5.8 $ 320.21 $ 39 23,296 $ 272.56 $ 4 Total (1) 1,387,366 4.2 $ 225.20 $ 300 610,289 $ 177.65 $ 161 (1) As at December 31, 2020, the total number of in-the-money stock options outstanding was 1,387,366 with a weighted-average exercise price of $225.20. The weighted-average years to expiration of exercisable stock options is 3.6 years.
Weighted-Average Fair Value Assumptions	The weighted-average fair value assumptions were approximately: 2020 2019 2018 Expected option life (years) (1) 4.75 5.00 5.00 Risk-free interest rate (2) 1.28 % 2.22 % 2.22 % Expected stock price volatility (3) 23.14 % 25.04 % 24.81 % Expected annual dividends per share (4) $ 3.3200 $ 2.6191 $ 2.3854 Expected forfeiture rate (5) 4.41 % 6.05 % 4.70 % Weighted-average grant date fair value of options granted during the year $ 69.00 $ 63.69 $ 55.63 (1) Represents the period of time that awards are expected to be outstanding. Historical data on exercise behaviour or, when available, specific expectations regarding future exercise behaviour were used to estimate the expected life of the option. (2) Based on the implied yield available on zero-coupon government issues with an equivalent term commensurate with the expected term of the option. (3) Based on the historical volatility of the Company’s stock price over a period commensurate with the expected term of the option. (4) Determined by the current annual dividend at the time of grant. The Company does not employ different dividend yields throughout the contractual term of the option. On July 21, 2020, the Company announced an increase in its quarterly dividend to $0.9500 per share, representing $3.8000 on an annual basis. (5) The Company estimates forfeitures based on past experience. The rate is monitored on a periodic basis.
Schedule of Options Exercised	The following table provides information related to all options exercised in the stock option plan during the years ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Total intrinsic value $ 52 $ 63 $ 17 Cash received by the Company upon exercise of options 52 26 24
Summary of Performance Share Unit Plan	The following table summarizes information related to the Company’s PSUs and PDSUs as at December 31: 2020 2019 Outstanding, January 1 403,136 395,048 Granted 108,027 134,260 Units, in lieu of dividends 3,843 4,032 Settled (121,225) (117,228) Forfeited (11,912) (12,976) Outstanding, December 31 381,869 403,136
Summary of Deferred Share Unit Plan	The following table summarizes information related to the DSUs as at December 31: 2020 2019 Outstanding, January 1 161,219 152,760 Granted 19,041 19,912 Units, in lieu of dividends 1,511 1,608 Settled (26,788) (12,110) Forfeited (172) (951) Outstanding, December 31 154,811 161,219
Summary of Share-Based Liabilities Paid	The following table summarizes the total share-based liabilities paid for each of the years ended December 31: (in millions of Canadian dollars) 2020 2019 2018 Plan PSUs $ 76 $ 54 $ 30 DSUs 9 4 6 Other 1 — 1 Total $ 86 $ 58 $ 37

Segmented and Geographic Info_2

Segmented and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Geographic Information	Geographic information All of the company's revenue and long-lived assets excluding financial instruments are held within Canada and the United States. (in millions of Canadian dollars) Canada United States Total 2020 Revenues $ 5,829 $ 1,881 $ 7,710 Long-term assets excluding financial instruments and pension assets 14,258 7,165 21,423 2019 Revenues 5,675 2,117 7,792 Long-term assets excluding financial instruments and pension assets 13,131 7,020 20,151 2018 Revenues 5,232 2,084 7,316 Long-term assets excluding financial instruments and pension assets 12,133 6,759 18,892

Selected Quarterly Data (Unau_2

Selected Quarterly Data (Unaudited) Selected Quarterly Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	For the quarter ended 2020 2019 (in millions of Canadian dollars, except per share data) Dec. 31 Sep. 30 Jun. 30 Mar. 31 Dec. 31 Sep. 30 Jun. 30 Mar. 31 Total revenues $ 2,012 $ 1,863 $ 1,792 $ 2,043 $ 2,069 $ 1,979 $ 1,977 $ 1,767 Operating income 928 779 770 834 890 869 822 543 Net income 802 598 635 409 664 618 724 434 Basic earnings per share (1) $ 5.97 $ 4.42 $ 4.68 $ 2.99 $ 4.84 $ 4.47 $ 5.19 $ 3.10 Diluted earnings per share (1) $ 5.95 $ 4.41 $ 4.66 $ 2.98 $ 4.82 $ 4.46 $ 5.17 $ 3.09 (1) Earnings per share for the four quarters combined may not equal earnings per share for the year due to rounding.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies [Line items]
Probability threshold for recognizing income tax benefits to be realized upon settlement	50.00%
Short-term investments maturity, maximum	3 months
Market-related asset value, Maximum percentage	120.00%
Market-related asset value, Minimum percentage	80.00%
Unrecognized actuarial gains and losses, Maximum percentage	10.00%
Expected average remaining service period of active employees expected to receive benefits	12 years
Intangible assets with finite lives amortization periods | Minimum
Summary of Significant Accounting Policies [Line items]
Amortization period of intangible assets with finite lives (years)	15 years
Intangible assets with finite lives amortization periods | Maximum
Summary of Significant Accounting Policies [Line items]
Amortization period of intangible assets with finite lives (years)	20 years

Accounting Changes - Narrative

Accounting Changes - Narrative (Details) $ in Millions	Jan. 01, 2020CAD ($)
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of the adoption of ASC 326	$ 1

- Disaggregation of Revenue (De

- Disaggregation of Revenue (Details) - CAD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 7,648	$ 7,729	$ 7,254
Leasing revenues									62	63	62
Total revenues	$ 2,012	$ 1,863	$ 1,792	$ 2,043	$ 2,069	$ 1,979	$ 1,977	$ 1,767	7,710	7,792	7,316
Freight
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									7,541	7,613	7,152
Total revenues									7,541	7,613	7,152
Grain
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,829	1,684	1,566
Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									566	682	673
Potash
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									493	462	486
Fertilizers and sulphur
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									290	250	243
Forest products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									328	304	284
Energy, chemicals and plastics
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,519	1,534	1,243
Metals, minerals and consumer products
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									629	752	797
Automotive
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									324	352	322
Intermodal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,563	1,593	1,538
Non-freight excluding leasing revenues
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 107	$ 116	$ 102

- Contract Liabilities (Details

- Contract Liabilities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Liability [Abstract]
Opening balance	$ 146	$ 2
Revenue recognized that was included in the contract liability balance at the beginning of the period	(100)	(2)
Increase due to consideration received, net of revenue recognized during the period	15	146
Closing balance	$ 61	$ 146

Other expense (income) (Details

Other expense (income) (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Foreign exchange (gain) loss on debt and lease liabilities	$ (14)	$ (94)	$ 168
Other foreign exchange (gains) losses	(1)	(4)	3
Other	8	9	3
Other (income) expense	$ (7)	$ (89)	$ 174

Net Interest Expense (Details)

Net Interest Expense (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Income (Expense), Net [Abstract]
Interest cost	$ 478	$ 471	$ 475
Interest capitalized to Properties	(16)	(17)	(20)
Interest expense	462	454	455
Interest income	(4)	(6)	(2)
Net interest expense	$ 458	$ 448	$ 453

Net Interest Expense - Narrativ

Net Interest Expense - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Income (Expense), Net [Abstract]
Interest on finance leases	$ 11	$ 11	$ 11

Income Taxes - Summary of Major

Income Taxes - Summary of Major Components of Company's Income Tax Expense (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current income tax expense	$ 537	$ 525	$ 381
Origination and reversal of temporary differences	277	316	214
Effect of tax rate decrease	(32)	(95)	(21)
Effect of hedge of net investment in foreign subsidiaries	(18)	(38)	64
Other	(6)	(2)	(1)
Total deferred income tax expense (recovery)	221	181	256
Income tax expense	758	706	637
Income before income tax expense
Canada	2,518	2,392	1,788
Foreign	684	754	800
Income before income tax expense	3,202	3,146	2,588
Current
Canada	412	410	336
Foreign	125	115	45
Total current income tax expense	537	525	381
Deferred
Canada	231	141	174
Foreign	(10)	40	82
Total deferred income tax expense (recovery)	221	181	256
Income tax expense	$ 758	$ 706	$ 637

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred income tax assets
Amount related to tax losses carried forward	$ 17	$ 6
Liabilities carrying value in excess of tax basis	131	139
Unrealized foreign exchange losses	4	26
Environmental remediation costs	22	22
Other	4	4
Total net deferred income tax assets	178	197
Deferred income tax liabilities
Properties carrying value in excess of tax basis	3,708	3,524
Pensions carrying value in excess of tax basis	43	83
Other	93	91
Total deferred income tax liabilities	3,844	3,698
Total net deferred income tax liabilities	$ 3,666	$ 3,501

Income Taxes - Expected Income

Income Taxes - Expected Income Tax Expense at Canadian Statutory Rates Reconciled to Income Tax Expense (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory federal and provincial income tax rate (Canada)	26.31%	26.77%	26.86%
Expected income tax expense at Canadian enacted statutory tax rates	$ 842	$ 842	$ 695
(Gains) losses not subject to tax	(23)	(19)	8
Canadian tax rate differentials	(3)	0	0
Foreign tax rate differentials	(32)	(33)	(55)
Effect of tax rate decrease	(32)	(95)	(21)
Valuation allowance	0	(5)	5
Unrecognized tax benefits	(7)	33	0
Other	13	(17)	5
Income tax expense	$ 758	$ 706	$ 637

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Uncertain Tax Positions Related to Unrecognized Tax Benefits (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Uncertain Tax Positions to Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits at January 1	$ 52	$ 13	$ 13
Tax benefits related to the current year	0	9	1
Tax benefits related to prior years	10	34	0
Gross uncertain tax benefits related to prior years	(9)	0	(1)
Settlements with taxing authorities	2
Settlements with taxing authorities		(4)	0
Unrecognized tax benefits at December 31	$ 55	$ 52	$ 13

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred revaluation recovery amount due to change in tax rate	$ (29)	$ (88)
Effect of tax rate decrease	32	95	$ 21
Income tax operating losses carried forward	15	4
Minimum tax credits carried forward	0
Unrecognized tax benefits from capital losses	2	2
Investment tax credits carried forward	0
Unrecognized tax benefits from capital losses	0	0
Unrecognized Tax Benefits		24
Income Tax Examination, Penalties and Interest Recovery	1	1	0
Accrued interest and penalties associated with unrecognized tax benefits	$ 9	$ 10	$ 11

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive options outstanding	1.4	1.6	1.3
Stock Option Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of options excluded from the computation of diluted earnings per share	0	0	0.2

Earnings Per Share - Number Of

Earnings Per Share - Number Of Shares Used In the Earnings Per Share Calculations (Details) - CAD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 802	$ 598	$ 635	$ 409	$ 664	$ 618	$ 724	$ 434	$ 2,444	$ 2,440	$ 1,951
Weighted-average basic shares outstanding									135.5	138.8	142.9
Dilutive effect of weighted average number of stock options									0.5	0.5	0.4
Weighted-average diluted shares outstanding									136	139.3	143.3
Earnings per share - basic	$ 5.97	$ 4.42	$ 4.68	$ 2.99	$ 4.84	$ 4.47	$ 5.19	$ 3.10	$ 18.05	$ 17.58	$ 13.65
Earnings per share - diluted	$ 5.95	$ 4.41	$ 4.66	$ 2.98	$ 4.82	$ 4.46	$ 5.17	$ 3.09	$ 17.97	$ 17.52	$ 13.61

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss - Components of Other Comprehensive Income (Loss) and Related Tax Effects (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrealized foreign exchange (loss) gain on: Before tax amount
Translation of the net investment in U.S. subsidiaries, before tax	$ (118)	$ (251)	$ 419
Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries, before tax	136	288	(479)
Realized loss on derivatives designated as cash flow hedges recognized in income, before tax	9	10	10
Unrealized gain on cash flow hedges and other, before tax			28
Change in pension and other benefits actuarial gains and losses, before tax	(403)	(661)	(447)
Change in prior service pension and other benefit costs, before tax	(4)		(2)
Other comprehensive (loss) income: Before tax amount	(380)	(614)	(471)
Unrealized foreign exchange gain (loss) on: Income tax (expense) recovery
Translation of the net investment in U.S. subsidiaries, tax	0	0	0
Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries, tax	(18)	(38)	64
Realized loss on cash flow hedges recognized in income, tax	(3)	(2)	(3)
Unrealized gain on cash flow hedges and other, tax			(8)
Change in pension and other benefits actuarial gains and losses, tax	108	175	115
Change in prior service pension and other benefit costs, tax	1		1
Other comprehensive (loss) income: Income tax (expense) recovery	88	135	169
Unrealized foreign exchange gain (loss) on: Net of tax amount
Translation of the net investment in U.S. subsidiaries, after tax	(118)	(251)	419
Translation of the U.S. dollar-denominated long-term debt designated as a hedge of the net investment in U.S. subsidiaries, after tax	118	250	(415)
Realized loss on derivatives designated as cash flow hedges recognized in income, after tax	6	8	7
Unrealized gain (loss) on cash flow hedges and other, after tax			(20)
Change in pension and other benefits actuarial gains and losses, after tax	(295)	(486)	(332)
Change in prior service pension and other benefit costs, after tax	(3)		(1)
Other comprehensive income (loss)	$ (292)	$ (479)	$ (302)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss, Net of Tax (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized foreign exchange gain (loss) on net investment	$ 493	$ 611
Net deferred losses on derivatives and other	(48)	(54)
Amounts for defined benefit pension and other post-retirement plans not recognized in income	(2,878)	(2,580)
Accumulated other comprehensive loss	(2,814)	(2,522)	$ (2,043)
Net Investment Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized foreign exchange gain (loss) on net investment	$ (381)	$ (499)

Other Comprehensive Income (L_5

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOC Income (Loss), Opening balance	$ (2,522)	$ (2,043)
Other comprehensive loss before reclassifications	(432)	(551)
Amounts reclassified from accumulated other comprehensive loss	140	72
Net other comprehensive income (loss)	(292)	(479)
AOC Income (Loss), Ending balance	(2,814)	(2,522)
Foreign currency net of hedging activities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOC Income (Loss), Opening balance	112	113
Other comprehensive loss before reclassifications	0	(1)
Amounts reclassified from accumulated other comprehensive loss	0	0
Net other comprehensive income (loss)	0	(1)
AOC Income (Loss), Ending balance	112	112
Derivatives and other
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOC Income (Loss), Opening balance	(54)	(62)
Other comprehensive loss before reclassifications	(2)	0
Amounts reclassified from accumulated other comprehensive loss	8	8
Net other comprehensive income (loss)	6	8
AOC Income (Loss), Ending balance	(48)	(54)
Pension and post-retirement defined benefit plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOC Income (Loss), Opening balance	(2,580)	(2,094)
Other comprehensive loss before reclassifications	(430)	(550)
Amounts reclassified from accumulated other comprehensive loss	132	64
Net other comprehensive income (loss)	(298)	(486)
AOC Income (Loss), Ending balance	$ (2,878)	$ (2,580)

Other Comprehensive Income (L_6

Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss - Amounts in Pension and Post-Retirement Defined Benefit Plans Reclassification from AOCL (Details) - Reclassification out of Accumulated Other Comprehensive Income [Member] - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service costs	$ (1)	$ 0
Recognition of net actuarial loss	180	84
Total before income tax	179	84
Income tax recovery	(47)	(20)
Total net of income tax	$ 132	$ 64

Accounts Receivable, Net - Sche

Accounts Receivable, Net - Schedule of Accounts Receivable (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 865		$ 847
Allowance for credit losses	(40)	$ (43)	(42)
Total accounts receivable, net	825		805
Freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	662		637
Allowance for credit losses	(25)	(27)	(26)
Total accounts receivable, net	637		611
Non-freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	203		210
Allowance for credit losses	(15)	$ (16)	(16)
Total accounts receivable, net	$ 188		$ 194

Accounts Receivable, Net - Allo

Accounts Receivable, Net - Allowance for Credit Loss (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses, opening balance	$ (42)
Current period credit loss provision, net	3
Allowance for credit loss, closing balance	(40)
Freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses, opening balance	(26)
Current period credit loss provision, net	2
Allowance for credit loss, closing balance	(25)
Non-freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses, opening balance	(16)
Current period credit loss provision, net	1
Allowance for credit loss, closing balance	$ (15)

Business combination - Narrativ

Business combination - Narrative (Details) $ in Millions	Dec. 22, 2020CAD ($)mi	Jun. 03, 2020CAD ($)	Dec. 30, 2019CAD ($)mi	Jun. 02, 2020CAD ($)	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2018CAD ($)
Business Acquisition [Line Items]
Investment in Detroit River Tunnel Partnership					$ 398	$ 0	$ 0
Book value of previously held equity method investment					150	166
Goodwill					329	194	$ 194
DRTP
Business Acquisition [Line Items]
Percentage of Voting Interests Acquired	83.50%
Investment in Detroit River Tunnel Partnership	$ 398
Reduction of operating costs related to movements through the DRTP					(34)
Miles of rail tunnel acquired | mi	1.6
Previously held equity interest, Percentage	16.50%
Gain on remeasurement of DRTP equity interest	$ 68
Fair value of previously held equity method investment	81
Book value of previously held equity method investment	13
Goodwill	90
Intangible assets	4
Acquired cash and equivalents	$ 6
CMQ
Business Acquisition [Line Items]
Investment in Detroit River Tunnel Partnership						174
Book value of previously held equity method investment					$ 0	$ 127
Additional consideration paid, working capital adjustment				$ 3
CMQ U.S.
Business Acquisition [Line Items]
Fair value of previously held equity method investment		$ 138
Goodwill		52
Intangible assets		27
Acquired cash and equivalents		$ 22
Finite-Lived Intangible Asset, Useful Life		20 years
CMQ Canada
Business Acquisition [Line Items]
Investment in Detroit River Tunnel Partnership			$ 47
Goodwill			10
Intangible assets			$ 5
Canada | CMQ
Business Acquisition [Line Items]
Miles of rail lines acquired | mi			237
United States | CMQ
Business Acquisition [Line Items]
Miles of rail lines acquired | mi			244

Business combination - FV of Ne

Business combination - FV of Net Assets Acquired DRTP (Details) - CAD ($) $ in Millions	Dec. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 329	$ 194	$ 194
Investment in Detroit River Tunnel Partnership		$ 398	$ 0	$ 0
DRTP
Business Acquisition [Line Items]
Accounts receivable, net	$ 5
Properties	436
Intangible assets	4
Accounts payable and accrued liabilities	(1)
Deferred taxes	(55)
Total identifiable assets and liabilities	389
Goodwill	90
Fair value of net assets acquired	479
Investment in Detroit River Tunnel Partnership	398
Fair value of previously held equity method investment	81
Total consideration	$ 479

Business combination - FV of _2

Business combination - FV of Net Assets Acquired CMQ U.S. (Details) - CAD ($) $ in Millions	Jun. 03, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 329	$ 194	$ 194
CMQ U.S.
Business Acquisition [Line Items]
Measurement period adjustment, Other long-term liabilities		$ 1
Cash and cash equivalents	$ 22
Accounts receivable, net	2
Properties	54
Intangible assets	27
Accounts payable and accrued liabilities	(13)
Other long-term liabilities	(6)
Total identifiable assets and liabilities	86
Goodwill	52
Fair value of net assets acquired	138
Fair value of previously held equity method investment	$ 138

Business combination - FV of _3

Business combination - FV of Net Assets Acquired CMQ Canada (Details) - CAD ($) $ in Millions	Dec. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 329	$ 194	$ 194
Investment in CMQ Canada		$ 398	$ 0	$ 0
CMQ Canada
Business Acquisition [Line Items]
Accounts receivable, net	$ 7
Properties	42
Intangible assets	5
Accounts payable and accrued liabilities	(2)
Long-term debt maturing within one year	(11)
Other long-term liabilities	(4)
Total identifiable assets and liabilities	37
Goodwill	10
Fair value of net assets acquired	47
Investment in CMQ Canada	$ 47

Investments (Details)

Investments (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Rail investments accounted for on an equity basis	$ 150	$ 166
Other investments	49	48
Total investments	199	341
CMQ
Schedule of Equity Method Investments [Line Items]
Rail investments accounted for on an equity basis	$ 0	$ 127

Properties - Net Properties (De

Properties - Net Properties (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Cost	$ 29,051	$ 27,255
Accumulated depreciation	8,629	8,099
Net book value	20,422	19,156
Capitalized internal-use software, Costs	45	55	$ 53
Capitalized internal-use software, Depreciation	$ 42	44	$ 49
Track and roadway
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.80%
Cost	$ 20,676	19,299
Accumulated depreciation	5,859	5,522
Net book value	$ 14,817	13,777
Buildings
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.90%
Cost	$ 937	833
Accumulated depreciation	259	237
Net book value	$ 678	596
Rolling stock
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.80%
Cost	$ 4,702	4,529
Accumulated depreciation	1,498	1,445
Net book value	$ 3,204	3,084
Information systems software
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	9.30%
Cost	$ 569	527
Accumulated depreciation	253	215
Net book value	$ 316	312
Other
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	5.20%
Cost	$ 2,167	2,067
Accumulated depreciation	760	680
Net book value	$ 1,407	$ 1,387

Properties - Capital Leases Inc

Properties - Capital Leases Included in Properties (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finance Leased Assets [Line Items]
Cost	$ 310	$ 307
Accumulated depreciation	139	130
Net book value	171	177
Rolling stock
Finance Leased Assets [Line Items]
Cost	302	303
Accumulated depreciation	138	130
Net book value	164	173
Other
Finance Leased Assets [Line Items]
Cost	8	4
Accumulated depreciation	1	0
Net book value	$ 7	$ 4

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill
Opening balance	$ 194	$ 194
Additions	142	10
Foreign exchange impact	(7)	(10)
Ending balance	329	194
Intangible assets
Cost, Opening balance	27	22
Accumulated amortization, Opening balance	(15)	(14)
Net carrying amount, Opening balance	12	8
Additions	31	5
Amortization	(3)	(1)
Foreign exchange impact	(3)
Cost, Ending balance	55	27
Accumulated amortization, Ending balance	(18)	(15)
Net carrying amount, Ending balance	37	12
Opening Balance	206	202
Additions	173	15
Amortization	(3)	(1)
Foreign exchange impact	(10)	(10)
Ending Balance	$ 366	$ 206

Other Assets (Details)

Other Assets (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Operating lease ROU assets	$ 316	$ 358
Contracted customer incentives	60	32
Long-term materials	37	41
Other	25	20
Total other assets	$ 438	$ 451

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Trade payables	$ 401	$ 453
Accrued charges	294	348
Accrued interest	134	131
Dividends payable	127	114
Stock-based compensation liabilities	121	85
Income and other taxes payable	115	139
Payroll-related accruals	68	78
Accrued vacation	59	60
Personal injury and other claims provision	37	55
Deferred revenue	27	142
Deferred real estate lease and license revenue	11	10
Provision for environmental remediation	9	7
Other(1)	1	2
Accounts payable and accrued liabilities	$ 1,467	$ 1,693

Debt - Narrative (Details)

Debt - Narrative (Details) $ in Millions, $ in Millions	Dec. 31, 2020CAD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Long-term debt and finance lease obligation, Current and non-current	$ 9,833		$ 8,816
Annual maturities and principal repayments in 2021	1,178
Annual maturities and principal repayments in 2022	471
Annual maturities and principal repayments in 2023	475
Annual maturities and principal repayments in 2024	83
Annual maturities and principal repayments in 2025	$ 891
U.S dollar-denominated
Debt Instrument [Line Items]
Long-term debt and finance lease obligation, Current and non-current		$ 6,713		$ 6,016

Debt - Components of Long-term

Debt - Components of Long-term Debt (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2018
Debt Instrument [Line Items]
Long-term debt, including unamortized fees	$ 9,833	$ 8,816
Long-term debt and finance lease obligation, excluding perpetual debt	9,788	8,771
Unamortized fees on long-term debt	(62)	(59)
Long-term debt, including current debt	9,771	8,757
Long-term debt maturing within one year	1,186	599
Long-term debt	$ 8,585	$ 8,158
9.450% 30-year Debentures
Debt Instrument [Line Items]
Interest rate	9.45%	9.45%
Maturity date	Aug. 1, 2021
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 318	$ 325
5.100% 10-year Medium Term Notes
Debt Instrument [Line Items]
Interest rate	5.10%	5.10%
Maturity date	Jan. 14, 2022
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 125	$ 125
4.500% 10-year Notes
Debt Instrument [Line Items]
Interest rate	4.50%	4.50%
Maturity date	Jan. 15, 2022
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 318	$ 324
4.450% 12.5-year Notes
Debt Instrument [Line Items]
Interest rate	4.45%	4.45%
Maturity date	Mar. 15, 2023
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 445	$ 454
2.900% 10-year Notes
Debt Instrument [Line Items]
Interest rate	2.90%	2.90%
Maturity date	Feb. 1, 2025
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 891	$ 909
3.700% 10.5-year Notes
Debt Instrument [Line Items]
Interest rate	3.70%	3.70%
Maturity date	Feb. 2, 2026
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 318	$ 324
4.000% 10-year Notes
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%	4.00%
Maturity date	Jun. 1, 2028
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 636	$ 649
3.150% 10-year Notes
Debt Instrument [Line Items]
Interest rate	3.15%	3.15%
Maturity date	Mar. 13, 2029	Mar. 13, 2029
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 399	$ 399
2.050% 10-year Notes
Debt Instrument [Line Items]
Interest rate	2.05%
Maturity date	Mar. 5, 2030
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 636	$ 0
7.125% 30-year Debentures
Debt Instrument [Line Items]
Interest rate	7.125%	7.125%
Maturity date	Oct. 15, 2031
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 446	$ 454
5.750% 30-year Debentures
Debt Instrument [Line Items]
Interest rate	5.75%	5.75%
Maturity date	Mar. 15, 2033
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 312	$ 318
4.800% 20-year Notes
Debt Instrument [Line Items]
Interest rate	4.80%	4.80%
Maturity date	Sep. 15, 2035
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 381	$ 388
5.950% 30-year Notes
Debt Instrument [Line Items]
Interest rate	5.95%	5.95%
Maturity date	May 15, 2037
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 567	$ 578
6.450% 30-year Notes
Debt Instrument [Line Items]
Interest rate	6.45%	6.45%
Maturity date	Nov. 17, 2039
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 400	$ 400
5.750% 30-year Notes
Debt Instrument [Line Items]
Interest rate	5.75%	5.75%
Maturity date	Jan. 15, 2042
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 313	$ 319
4.800% 30-year Notes
Debt Instrument [Line Items]
Interest rate	4.80%	4.80%
Maturity date	Aug. 1, 2045
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 698	$ 712
3.050% 30-year Notes
Debt Instrument [Line Items]
Interest rate	3.05%
Maturity date	Mar. 9, 2050
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 298	$ 0
6.125% 100-year Notes
Debt Instrument [Line Items]
Interest rate	6.125%	6.125%
Maturity date	Sep. 15, 2115
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 1,146	$ 1,169
8.000% 5-year Promissory Notes
Debt Instrument [Line Items]
Interest rate	8.00%	8.00%
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 0	$ 11
5.41% Senior Secured Notes
Debt Instrument [Line Items]
Interest rate	5.41%	5.41%
Maturity date	Mar. 3, 2024
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 89	$ 100
6.91% Secured Equipment Notes
Debt Instrument [Line Items]
Interest rate	6.91%	6.91%
Maturity date	Oct. 1, 2024
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 75	$ 91
7.49% Equipment Trust Certificates
Debt Instrument [Line Items]
Interest rate	7.49%	7.49%
Maturity date	Jan. 15, 2021
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 14	$ 55
1.99-2.97% Finance Leases
Debt Instrument [Line Items]
Currency in which payable	CDN$/U.S.$
Long-term debt, including unamortized fees	$ 4	$ 3
1.99-2.97% Finance Leases | Minimum
Debt Instrument [Line Items]
Interest rate	1.99%	1.99%
Maturity date	Jul. 1, 2021
1.99-2.97% Finance Leases | Maximum
Debt Instrument [Line Items]
Interest rate	2.97%	2.97%
Maturity date	Mar. 1, 2023
6.99% Finance Lease
Debt Instrument [Line Items]
Interest rate	6.99%	6.99%
Maturity date	Mar. 12, 2022
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 97	$ 99
6.57% Finance Lease
Debt Instrument [Line Items]
Interest rate	6.57%	6.57%
Maturity date	Dec. 30, 2026
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 38	$ 45
12.77% Finance Lease
Debt Instrument [Line Items]
Interest rate	12.77%	12.77%
Maturity date	Jan. 1, 2031
Currency in which payable	CDN$
Long-term debt, including unamortized fees	$ 4	$ 4
Commercial Paper
Debt Instrument [Line Items]
Currency in which payable	U.S.$
Commercial paper	$ 820	$ 516
Commercial Paper | Maximum
Debt Instrument [Line Items]
Maturity date	Feb. 9, 2021
Perpetual 4% Consolidated Debenture Stock (USD)
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%
Currency in which payable	U.S.$
Long-term debt, including unamortized fees	$ 39	$ 39
Perpetual 4% Consolidated Debenture Stock (GBP)
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%
Currency in which payable	G.B.£
Long-term debt, including unamortized fees	$ 6	$ 6

Debt - Components of Long-ter_2

Debt - Components of Long-term Debt - (Narrative) (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018CAD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	$ 958		$ 397		$ 638
Finance lease, ROU asset	171		$ 177
7.250% 10-year Notes
Debt Instrument [Line Items]
Interest rate			7.25%			7.25%
Debt instrument, Term			10 years	10 years
Extinguishment of debt, Amount			$ 471	$ 350
2.050% 10-year Notes
Debt Instrument [Line Items]
Debt instrument, Face amount	$ 500
Interest rate	2.05%
Debt instrument, Term	10 years	10 years
Maturity date	Mar. 5, 2030	Mar. 5, 2030
Proceeds from issuance of debt	$ 662	$ 495
3.050% 30-year Notes
Debt Instrument [Line Items]
Debt instrument, Face amount	$ 300
Interest rate	3.05%
Debt instrument, Term	30 years	30 years
Maturity date	Mar. 9, 2050	Mar. 9, 2050
Proceeds from issuance of debt	$ 296
3.150% 10-year Notes
Debt Instrument [Line Items]
Debt instrument, Face amount			$ 400
Interest rate	3.15%		3.15%			3.15%
Debt instrument, Term			10 years	10 years
Maturity date	Mar. 13, 2029	Mar. 13, 2029	Mar. 13, 2029	Mar. 13, 2029
Proceeds from issuance of debt	$ 397
8.000% 5-year Promissory Notes
Debt Instrument [Line Items]
Interest rate	8.00%		8.00%			8.00%
Debt instrument, Term			5 years	5 years
Assumed obligations of CMQ Canada from business combination			$ 11			$ 8
5.41% Senior Secured Notes
Debt Instrument [Line Items]
Interest rate	5.41%		5.41%			5.41%
Maturity date	Mar. 3, 2024	Mar. 3, 2024
Value of locomotive units used as collateral	$ 97
Final repayment of principal amount		$ 44
6.91% Secured Equipment Notes
Debt Instrument [Line Items]
Interest rate	6.91%		6.91%			6.91%
Maturity date	Oct. 1, 2024	Oct. 1, 2024
Value of locomotive units used as collateral	$ 54
Final repayment of principal amount	$ 11
7.49% Equipment Trust Certificates
Debt Instrument [Line Items]
Interest rate	7.49%		7.49%			7.49%
Maturity date	Jan. 15, 2021	Jan. 15, 2021
Value of locomotive units used as collateral	$ 91
Final repayment of principal amount		$ 11

Debt - Credit Facility (Narrati

Debt - Credit Facility (Narrative) (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020CAD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019CAD ($)
Commercial Paper
Debt Instrument [Line Items]
Commercial paper		$ 820	$ 644	$ 516
Weighted-average interest rate, Commercial paper		0.27%	0.27%	2.03%
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, Total available amount			$ 1,300
U.S. $1.0 Billion Tranche
Debt Instrument [Line Items]
Credit facility, Total available amount			1,000
U.S. $300 Million Tranche
Debt Instrument [Line Items]
Credit facility, Total available amount			$ 300
Credit facility, Drawn	$ 100
Letters of Credit
Debt Instrument [Line Items]
Letters of Credit, Drawn		$ 59		$ 80
Maximum capacity under credit facility		$ 300		$ 300

Financial Instruments - FV and

Financial Instruments - FV and CV of Long-term Debt (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Long-term debt, excluding Commercial Paper	$ 8,951	$ 8,241
Long-term Debt, Fair value	$ 11,597	$ 10,149

Financial Instruments (Details)

Financial Instruments (Details) $ in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018CAD ($)	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2018CAD ($)	Jun. 30, 2018USD ($)
4.000% 10-year Notes
Schedule of Investments [Line Items]
Debt instrument, Face amount					$ 500
Interest rate	4.00%	4.00%	4.00%		4.00%
Debt instrument, Term	10 years
Forward Starting Swaps
Schedule of Investments [Line Items]
Floating-to-fixed interest rate swaps, Notional amount					$ 500
Fair value loss	$ 24				$ 19
Forward Starting Swaps | Net Interest Expense
Schedule of Investments [Line Items]
Derivative losses amortized to net interest expense		$ 9	$ 9	$ 10
Net losses expected to be recognized in next 12 months		9
Treasury Rate Locks
Schedule of Investments [Line Items]
Unamortized losses, Treasury rate locks		17	18
Treasury Rate Locks | Net Interest Expense
Schedule of Investments [Line Items]
Derivative losses amortized to net interest expense		1	1	1
Net losses expected to be recognized in next 12 months		1
Net Investment Hedge
Schedule of Investments [Line Items]
Gain (loss) on net investment hedge		$ 136	$ 288	$ (479)

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Disclosure [Abstract]
Stock-based compensation liabilities, net of current portion	$ 146	$ 111
Provision for environmental remediation, net of current portion	71	70
Deferred revenue, net of current portion	34	4
Deferred real estate lease and license revenue, net of current portion	18	20
Deferred gains on sale leaseback transactions	5	6
Other, net of current portion	63	66
Other long-term liabilities	585	562
Aggregate provision for environmental remediation, including current portion	$ 80	$ 77

Other Long-Term Liabilities - N

Other Long-Term Liabilities - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Expected time period for payment of provision for environmental remediation	10
Environmental remediation costs charged to income	$ 10	$ 6	$ 6

Narrative (Details)

Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)
Lessee, Lease, Description [Line Items]
Lessee, Operating lease, Option to extend	10 years
Lessee, Operating lease, Option to terminate	one year
Operating lease, Residual value guarantee	$ 1
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating lease, Term of contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating lease, Term of contract	14 years

Leases Components of Lease Expe

Leases Components of Lease Expense (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease cost	$ 83	$ 89
Short-term lease cost	10	10
Variable lease cost	13	13
Sublease Income	(3)	(3)
Finance lease, Amortization of right-of-use assets	9	9
Finance lease, Interest on lease liabilities	11	11	$ 11
Total lease costs	$ 123	$ 129

Leases Supplemental Balance She

Leases Supplemental Balance Sheet Information (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease, ROU asset	$ 316	$ 358
Finance lease, ROU asset	171	177
Finance lease, Liability, Current	8	7
Finance lease, Liability, Non-current	135	144
Other assets
Lessee, Lease, Description [Line Items]
Operating lease, ROU asset	316	358
Accounts payable and accrued liabilities
Lessee, Lease, Description [Line Items]
Operating lease, Liability, Current	63	69
Other long-term liabilities
Lessee, Lease, Description [Line Items]
Operating lease, Liability, Non-current	$ 248	$ 285

Leases Weighted Average Remaini

Leases Weighted Average Remaining Lease Terms and Discount Rates (Details)	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating leases, Weighted-average remaining lease term	7 years	7 years
Finance leases, Weighted-average remaining lease term	3 years	4 years
Operating leases, Weighted-average discount rate	3.32%	3.45%
Finance leases, Weighted-average discount rate	7.06%	7.07%

Leases Supplemental Information

Leases Supplemental Information Related to Leases (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating cash outflows from operating leases	$ 74	$ 82
Operating cash outflows from finance leases	10	10
Financing cash outflows from finance leases	8	6
Right-of-use assets obtained in exchange for operating lease liabilities	34	38
Right-of-use assets obtained in exchange for finance lease liabilities	$ 4	$ 4

Leases Maturities of Lease Liab

Leases Maturities of Lease Liabilities (Details) $ in Millions	Dec. 31, 2020CAD ($)
Leases [Abstract]
Finance Leases, Payments due 2021	$ 11
Finance Leases, Payments due 2022	107
Finance Leases, Payments due 2023	9
Finance Leases, Payments due 2024	8
Finance Leases, Payments due 2025	8
Finance Leases, Payments due thereafter	12
Finance Leases, Total lease payments	155
Finance Leases, Imputed interest	(12)
Finance Leases, Present value of lease payments	143
Operating Leases, Payments due 2021	71
Operating Leases, Payments due 2022	59
Operating Leases, Payments due 2023	53
Operating Leases, Payments due 2024	42
Operating Leases, Payments due 2025	34
Operating Leases, Payments due thereafter	88
Operating Leases, Total lease payments	347
Operating Leases, Imputed interest	(36)
Operating Leases, Present value of lease payments	$ 311

Shareholders Equity - Narrative

Shareholders Equity - Narrative (Details) - CAD ($) $ in Millions

Jan. 28, 2022

Dec. 19, 2019

Oct. 23, 2019

May 14, 2018

Dec. 31, 2020

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Jan. 27, 2021

Dec. 17, 2019

Oct. 19, 2018

May 10, 2017

Preferred shares issued

0

0

Common Shares repurchased

4,000,000

3,800,000

4,600,000

Common Shares repurchased (value)

$ 1,477

$ 1,140

$ 1,127

2019 Normal Course Issuer Bid

Common shares authorized to be repurchased

4,800,000

Share repurchase program expiration date

Dec. 19, 2020

Common Shares repurchased

4,270,000

3,973,076

Common Shares repurchased (value)

$ 1,577

$ 1,477

2018 Normal Course Issuer Bid

Common shares authorized to be repurchased

5,680,000

Share repurchase program expiration date

Oct. 23, 2019

2017 Normal Course Issuer Bid

Common shares authorized to be repurchased

4,380,000

Share repurchase program expiration date

May 14, 2018

2021 Normal Course Issuer Bid | 2021 NCIB Program Announcement

Common shares authorized to be repurchased

3,330,000

Share repurchase program expiration date

Jan. 28, 2022

Share capital

Stock-based compensation transferred from APIC

10

7

12

Common Shares repurchased (value)

$ 58

$ 54

$ 66

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Information Related to Common Share Balances (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share capital, January 1	137	140.5	144.9
CP Common Shares repurchased	(4)	(3.8)	(4.6)
Shares issued under stock option plan	0.3	0.3	0.2
Share capital, December 31	133.3	137	140.5

Shareholders' Equity - Activiti

Shareholders' Equity - Activities Under Shares Repurchase Program (Details) - CAD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Common Shares repurchased	4,000,000		3,800,000	4,600,000
Amount of repurchase (in millions)	$ 1,477		$ 1,140	$ 1,127
2019 Normal Course Issuer Bid
Number of Common Shares repurchased	3,973,076	4,270,000
Weighted-average price per share	$ 371.74
Amount of repurchase (in millions)	$ 1,477	$ 1,577
2018 & 2019 Normal Course Issuer Bids
Number of Common Shares repurchased			3,794,149
Weighted-average price per share			$ 300.65
Amount of repurchase (in millions)			$ 1,141
2017 & 2018 Normal Course Issuer Bids
Number of Common Shares repurchased				4,683,162
Weighted-average price per share				$ 240.68
Amount of repurchase (in millions)				$ 1,127

Change in Non-Cash Working Ca_3

Change in Non-Cash Working Capital Balances Related to Operations - Change in Non-Cash Working Capital Balances Related to Operations (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Accounts receivable, net	$ (61)	$ 27	$ (107)
Increase (Decrease) in Materials and Supplies	(15)	(8)	(11)
Other current assets	(5)	(24)	30
Accounts payable and accrued liabilities	(308)	(21)	153
Change in non-cash working capital, total	$ (389)	$ (26)	$ 65

Pensions and Other Benefits - A

Pensions and Other Benefits - Additional Information (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Period of average market values for calculating net periodic benefit cost	5 years
DB Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 443	$ 419
DB Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	$ 187	$ 186
Maximum value of underlying assets represented by financial derivatives, excluding currency forwards	30.00%
Solvency funded position hedged against interest rate risk	47.00%	45.00%
Company's common shares in fund assets	109,008	119,758
Net cost of defined contribution plan	$ 12	$ 11	$ 10
Multi-employer benefit plan, Employer contributions	$ 3	$ 3	$ 3
US Dollar
Defined Benefit Plan Disclosure [Line Items]
Plans exposure to foreign currency risk percentage	33.00%	39.00%
Percentage of plan exposed to foreign currency risk, excluding currency forwards	40.00%	41.00%
Euro
Defined Benefit Plan Disclosure [Line Items]
Plans exposure to foreign currency risk percentage	6.00%	6.00%
Other Currencies
Defined Benefit Plan Disclosure [Line Items]
Plans exposure to foreign currency risk percentage	14.00%	14.00%
Public equities
Defined Benefit Plan Disclosure [Line Items]
Company's securities in fund assets	$ 48	$ 40
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
DB pension plans' accumulated benefit obligation	$ 13,528	$ 12,201

Pensions and Other Benefits - N

Pensions and Other Benefits - Net Periodic Benefit Cost (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total other components of net periodic benefit (recovery) cost	$ (342)	$ (381)	$ (384)
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Current service cost (benefits earned by employees)	140	107	120
Interest cost on benefit obligation	406	450	438
Expected return on fund assets	(945)	(947)	(955)
Recognized net actuarial loss	177	84	114
Amortization of prior service costs	(1)	(1)	(2)
Total other components of net periodic benefit (recovery) cost	(363)	(414)	(405)
Net periodic benefit (recovery) cost	(223)	(307)	(285)
Other Post-retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Current service cost (benefits earned by employees)	12	11	12
Interest cost on benefit obligation	17	20	19
Expected return on fund assets	0	0	0
Recognized net actuarial loss	4	12	2
Amortization of prior service costs	0	1	0
Total other components of net periodic benefit (recovery) cost	21	33	21
Net periodic benefit (recovery) cost	$ 33	$ 44	$ 33

Pensions and Other Benefits - C

Pensions and Other Benefits - Changes in Projected Benefit Obligation (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in projected benefit obligation:
Benefit obligation, Discount rate	2.58%	3.25%	4.01%
Pension Plan, Defined Benefit
Change in projected benefit obligation:
Benefit obligation at January 1	$ 12,610	$ 11,372
Current service cost	140	107	$ 120
Interest cost	406	450	438
Employee contributions	42	41
Benefits paid	(653)	(646)
Foreign currency changes	(5)	(10)
Plan amendments and other	3	0
Actuarial loss	1,256	1,296
Projected benefit obligation at December 31	$ 13,799	$ 12,610	$ 11,372
Benefit obligation, Discount rate	2.58%	3.25%	4.01%
Other Post-retirement Benefit Plans
Change in projected benefit obligation:
Benefit obligation at January 1	$ 541	$ 501
Current service cost	12	11	$ 12
Interest cost	17	20	19
Employee contributions	0	0
Benefits paid	(34)	(34)
Foreign currency changes	0	0
Plan amendments and other	0	0
Actuarial loss	17	43
Projected benefit obligation at December 31	$ 553	$ 541	$ 501

Pensions and Other Benefits -_2

Pensions and Other Benefits - Changes in Fund Assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of fund assets at January 1	$ 13,319
Fair value of fund assets at December 31	14,365	$ 13,319
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Fair value of fund assets at January 1	13,319	12,349
Actual return on fund assets	1,634	1,528
Employer contributions	27	53
Employee contributions	42	41
Benefits paid	(653)	(646)
Foreign currency changes	(4)	(6)
Fair value of fund assets at December 31	14,365	13,319
Funded status – plan surplus (deficit)	566	709
Other Post-retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of fund assets at January 1	5	4
Actual return on fund assets	0	1
Employer contributions	34	34
Employee contributions	0	0
Benefits paid	(34)	(34)
Foreign currency changes	0	0
Fair value of fund assets at December 31	5	5
Funded status – plan surplus (deficit)	$ (548)	$ (536)

Pensions and Other Benefits - F

Pensions and Other Benefits - Funded Status of Pension Plans (Details) - Pension Plan, Defined Benefit - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension plans in deficit
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at December 31	$ (579)	$ (534)
Fair value of fund assets at December 31	251	240
Funded Status	(328)	(294)
Pension plans in surplus
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at December 31	(13,220)	(12,076)
Fair value of fund assets at December 31	14,114	13,079
Funded Status	$ 894	$ 1,003

Pensions and Other Benefits -_3

Pensions and Other Benefits - Amounts Recognized in Company's Consolidated Balance Sheets (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Pension asset	$ 894	$ 1,003
Pension and other benefit liabilities	(832)	(785)
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Pension asset	894	1,003
Accounts payable and accrued liabilities	(11)	(11)
Pension and other benefit liabilities	(317)	(283)
Total amount recognized	566	709
Other Post-retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Pension asset	0	0
Accounts payable and accrued liabilities	(33)	(34)
Pension and other benefit liabilities	(515)	(502)
Total amount recognized	$ (548)	$ (536)

Pensions and Other Benefits -_4

Pensions and Other Benefits - Amounts Recognized in Accumulated Other Comprehensive Losses (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Amounts recognized in accumulated other comprehensive loss	$ 2,878	$ 2,580
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Other than deferred investment gains	3,960	3,434
Deferred investment gains	(95)	41
Prior service cost	5	1
Deferred income tax	(1,070)	(964)
Amounts recognized in accumulated other comprehensive loss	2,800	2,512
Other Post-retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Other than deferred investment gains	104	91
Deferred investment gains	0	0
Prior service cost	1	1
Deferred income tax	(27)	(24)
Amounts recognized in accumulated other comprehensive loss	$ 78	$ 68

Pensions and Other Benefits -_5

Pensions and Other Benefits - Actuarial Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, Discount rate		2.58%	3.25%	4.01%
Benefit obligation, Projected future salary increases		2.75%	2.75%	2.75%
Health care cost trend rate		5.50%	6.00%	7.00%
Benefit cost, Discount rate		3.25%	4.01%	3.80%
Benefit cost, Expected rate of return on fund assets		7.25%	7.50%	7.75%
Benefit cost, Projected future salary increases		2.75%	2.75%	2.75%
Health care cost trend rate change		0.50%
Ultimate health care cost trend rate		5.00%
Forecast
Defined Benefit Plan Disclosure [Line Items]
Benefit cost, Expected rate of return on fund assets	6.90%

Pensions and Other Benefits - P

Pensions and Other Benefits - Pension Plan Asset Allocation and Weighted-Average Policy Range (Details) - Pension Plan, Defined Benefit	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	100.00%
Percentage of plan assets	100.00%	100.00%
Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	1.20%
Percentage of plan assets	2.00%	0.90%
Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	24.10%
Percentage of plan assets	28.10%	24.60%
Public equities
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	45.10%
Percentage of plan assets	49.30%	54.50%
Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	9.80%
Percentage of plan assets	6.30%	6.80%
Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	9.80%
Percentage of plan assets	3.30%	2.40%
Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	10.00%
Percentage of plan assets	11.00%	10.80%
Minimum | Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	—
Minimum | Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	20
Minimum | Public equities
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	35
Minimum | Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	4
Minimum | Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	4
Minimum | Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	4
Maximum | Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	10
Maximum | Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	40
Maximum | Public equities
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	55
Maximum | Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	13
Maximum | Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	13
Maximum | Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Weighted-average policy range	13

Pensions and Other Benefits - S

Pensions and Other Benefits - Summary of DB Pension Plan Assets at Fair Value (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	$ 14,365	$ 13,319
Currency Forward
Defined Benefit Plan Disclosure [Line Items]
Derivative, Notional Amount	1,041	334
Derivative, Fair Value, Net	73	13
Bond Forward
Defined Benefit Plan Disclosure [Line Items]
Derivative, Notional Amount	3,540	3,269
Derivative, Fair Value, Net	(2)	(72)
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	219	112
Government bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,983	2,090
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,835	1,092
Mortgages
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	225	164
Public equities, Canada
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,183	1,351
Public equities, U.S and international
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	5,899	5,905
Real estate
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	704	724
Fund value subject to redemption	580	606
Fund value not subject to redemption	124	118
Unfunded commitments	32	35
Infrastructure
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	199	187
Fund value subject to redemption	112	119
Fund value not subject to redemption	87	68
Unfunded commitments	491	286
Private debt
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	465	313
Fund value subject to redemption	154	154
Fund value not subject to redemption	311	159
Unfunded commitments	533	392
Derivative instruments
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	71	(59)
Absolute return, Funds of hedge funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,560	1,418
Absolute return, Multi-strategy funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	22	22
Investments measured at NAV
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	2,950	2,664
Investments measured at NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Government bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Mortgages
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Public equities, Canada
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Public equities, U.S and international
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Real estate
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	704	724
Investments measured at NAV | Infrastructure
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	199	187
Investments measured at NAV | Private debt
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	465	313
Investments measured at NAV | Derivative instruments
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Investments measured at NAV | Absolute return, Funds of hedge funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,560	1,418
Investments measured at NAV | Absolute return, Multi-strategy funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	22	22
Fair Value, Level 1
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	8,468	8,011
Fair Value, Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	219	112
Fair Value, Level 1 | Government bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	284	233
Fair Value, Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	691	273
Fair Value, Level 1 | Mortgages
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	220	159
Fair Value, Level 1 | Public equities, Canada
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,183	1,351
Fair Value, Level 1 | Public equities, U.S and international
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	5,871	5,883
Fair Value, Level 1 | Real estate
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 1 | Infrastructure
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 1 | Private debt
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 1 | Derivative instruments
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 1 | Absolute return, Funds of hedge funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 1 | Absolute return, Multi-strategy funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	2,947	2,644
Fair Value, Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Government bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,699	1,857
Fair Value, Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	1,144	819
Fair Value, Level 2 | Mortgages
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	5	5
Fair Value, Level 2 | Public equities, Canada
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Public equities, U.S and international
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	28	22
Fair Value, Level 2 | Real estate
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Infrastructure
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Private debt
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Derivative instruments
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	71	(59)
Fair Value, Level 2 | Absolute return, Funds of hedge funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	0	0
Fair Value, Level 2 | Absolute return, Multi-strategy funds
Defined Benefit Plan Disclosure [Line Items]
DB pension plans at fair values	$ 0	$ 0

Pensions and Other Benefits - E

Pensions and Other Benefits - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2020CAD ($)
Pension Plan, Defined Benefit
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
2021	$ 632
2022	629
2023	631
2024	633
2025	635
2026 – 2030	3,203
Other Post-retirement Benefit Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
2021	33
2022	31
2023	31
2024	30
2025	30
2026 – 2030	$ 142

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020CAD ($)shares	Dec. 31, 2020CAD ($)shares	Dec. 31, 2019CAD ($)shares	Dec. 31, 2018CAD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 170	$ 133	$ 75
Share-based liabilities paid		86	58	37
Regular and Performance Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 16	14	10
Expiration period		7 years
Fair value of options at grant date		$ 15	14	16
Unrecognized compensation expense		$ 12
Weighted-average period of recognition for unrecognized compensation		1 year 1 month 6 days
Fair value of shares vested for stock option plan		$ 10	8	11
Regular and Performance Stock Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		12 months
Regular and Performance Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		48 months
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 89	$ 54
Units issued | shares		97,998	133,681	125,280
Grant date fair value		$ 34
Payout percentage		200.00%	193.00%
PSUs vested in period | shares		113,769
Fair value of PSUs vested in period		$ 98
Number of trading days			30 days
Share-based liabilities paid	$ 76	$ 76	$ 54	$ 30
PSUs units paid in period | shares	121,225		117,228
Performance Share Units | Retention Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued | shares			579	36,975
Performance Deferred Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued | shares		10,029
Grant date fair value		$ 4
Matching % of DSU's granted to senior managers		25.00%
PSUs and PDSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 121
Vesting period		3 years
Unrecognized compensation expense		$ 51
Weighted-average period of recognition for unrecognized compensation		1 year 4 months 24 days
Units issued | shares		108,027
Deferred Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 21	$ 20	$ 4
Vesting period		36 months
Unrecognized compensation expense		$ 1
Weighted-average period of recognition for unrecognized compensation		1 year 3 months 18 days
Units issued | shares		19,041	19,912
Grant date fair value		$ 7
Number of trading days		10 days
Share-based liabilities paid		$ 9	$ 4	6
PSUs units paid in period | shares		26,788	12,110
Matching % of DSU's granted to senior managers		25.00%
Ownership target period		5 years
Employee Share Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 7	$ 6	$ 5
Vesting period		1 year
Employer matching ratio per dollar contributed		0.3333
Maximum percentage of annual salary that an employee can contribute		6.00%
Number of shares purchased on behalf of participants | shares		115,344	137,942	118,865
Employer contributions		$ 9	$ 8	$ 6

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Plan (Details) - Stock Option Plan - CAD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of options, Options outstanding (in shares)
Outstanding, January 1, Options	1,416,346
Granted, Options	217,240
Exercised, Options	(232,034)
Forfeited, Options	(13,839)
Expired, Options	(347)
Outstanding, December 31, Options	1,387,366	1,416,346
Vested or expected to vest at December 31, Options	1,366,649
Exercisable, December 31, Options	610,289
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, January 1	$ 199.12
Granted	344.04
Exercised	162.87
Forfeited	271.75
Expired	168.84
Outstanding at December 31	225.20	$ 199.12
Vested or expected to vest as at December 31	223.98
Exercisable at December 31	$ 177.65
Number of options, Nonvested options (in shares)
Non-vested, Outstanding January 1, Options	761,784
Granted, Options	217,240
Vested, Options	(188,108)
Non-vested, Forfeited, Options	(13,839)
Non-vested, Outstanding December 31, Options	777,077	761,784
Weighted average grant date fair value, Nonvested options
Non-vested, Outstanding, January 1	$ 53.54
Non-vested, Granted	69	$ 63.69	$ 55.63
Vested	50.91
Non-vested, Forfeited	58.29
Non-vested, Outstanding, December 31	$ 58.40	$ 53.54
Weighted average remaining term of vested or expected to vest options	4 years 6 months
Aggregate intrinsic value of vested or expected to vest options	$ 297

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options Outstanding and Exercisable (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)$ / sharesshares
$65.06 - $188.78
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of exercise prices, minimum	$ 65.06
Range of exercise prices, maximum	188.78
$188.79 - $214.58
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of exercise prices, minimum	188.79
Range of exercise prices, maximum	214.58
$214.59 - $261.88
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of exercise prices, minimum	214.59
Range of exercise prices, maximum	261.88
$261.89 - $411.37
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of exercise prices, minimum	261.89
Range of exercise prices, maximum	411.37
Stock Option Plan
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Company's closing stock price (CAD)	$ 441.53
Options outstanding, Number of options | shares	1,387,366
Options outstanding, Weighted-average years to expiration	4 years 2 months 12 days
Options outstanding, Weighted-average exercise price	$ 225.20
Options outstanding, Aggregate intrinsic value | $	$ 300
Options exercisable, Number of options (in shares) | shares	610,289
Options exercisable, Weighted-average exercise price	$ 177.65
Options exercisable, Aggregate intrinsic value | $	$ 161
Number of stock options in-the-money | shares	1,387,366
Weighted-average exercise price of stock options in-the-money	$ 225.20
Weighted-average years to expiration	3 years 7 months 6 days
Stock Option Plan | $65.06 - $188.78
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, Number of options | shares	342,773
Options outstanding, Weighted-average years to expiration	3 years 4 months 24 days
Options outstanding, Weighted-average exercise price	$ 141.26
Options outstanding, Aggregate intrinsic value | $	$ 103
Options exercisable, Number of options (in shares) | shares	342,773
Options exercisable, Weighted-average exercise price	$ 141.26
Options exercisable, Aggregate intrinsic value | $	$ 103
Stock Option Plan | $188.79 - $214.58
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, Number of options | shares	327,811
Options outstanding, Weighted-average years to expiration	3 years 1 month 6 days
Options outstanding, Weighted-average exercise price	$ 196.82
Options outstanding, Aggregate intrinsic value | $	$ 80
Options exercisable, Number of options (in shares) | shares	109,375
Options exercisable, Weighted-average exercise price	$ 203.83
Options exercisable, Aggregate intrinsic value | $	$ 26
Stock Option Plan | $214.59 - $261.88
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, Number of options | shares	394,953
Options outstanding, Weighted-average years to expiration	4 years 4 months 24 days
Options outstanding, Weighted-average exercise price	$ 244.17
Options outstanding, Aggregate intrinsic value | $	$ 78
Options exercisable, Number of options (in shares) | shares	134,845
Options exercisable, Weighted-average exercise price	$ 232.54
Options exercisable, Aggregate intrinsic value | $	$ 28
Stock Option Plan | $261.89 - $411.37
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, Number of options | shares	321,829
Options outstanding, Weighted-average years to expiration	5 years 9 months 18 days
Options outstanding, Weighted-average exercise price	$ 320.21
Options outstanding, Aggregate intrinsic value | $	$ 39
Options exercisable, Number of options (in shares) | shares	23,296
Options exercisable, Weighted-average exercise price	$ 272.56
Options exercisable, Aggregate intrinsic value | $	$ 4

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted-Average Fair Value Assumptions (Details) - CAD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends declared per share	$ 0.9500	$ 3.5600	$ 3.1400	$ 2.5125
Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life (years)		4 years 9 months	5 years	5 years
Risk-free interest rate		1.28%	2.22%	2.22%
Expected stock price volatility		23.14%	25.04%	24.81%
Expected annual dividends per share		$ 3.3200	$ 2.6191	$ 2.3854
Estimated forfeiture rate		4.41%	6.05%	4.70%
Weighted average grant date fair value of options granted during the year		$ 69	$ 63.69	$ 55.63
Expected annual dividends per share		$ 3.8000

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Options Exercised (Details) - Stock Option Plan - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value	$ 52	$ 63	$ 17
Cash received by the Company upon exercise of options	$ 52	$ 26	$ 24

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Performance Share Units Plan (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] (in shares)
Outstanding, January 1	403,136	403,136	395,048
Granted		97,998	133,681	125,280
Units, in lieu of dividends			4,032
Settled	(121,225)		(117,228)
Forfeited			(12,976)
Outstanding, December 31			403,136	395,048
Performance Share Units | Regular and Retention Grant
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] (in shares)
Granted			134,260
Performance Deferred Share Units
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] (in shares)
Granted		10,029
PSUs and PDSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] (in shares)
Granted		108,027
Units, in lieu of dividends		3,843
Forfeited		(11,912)
Outstanding, December 31		381,869

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Deferred Share Units Plan (Details) - Deferred Share Units - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] (in shares)
Outstanding, January 1	161,219	152,760
Granted	19,041	19,912
Units, in lieu of dividends	1,511	1,608
Settled	(26,788)	(12,110)
Forfeited	(172)	(951)
Outstanding, December 31	154,811	161,219

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Total Share Based Liabilities (Details) - CAD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based liabilities paid		$ 86	$ 58	$ 37
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based liabilities paid	$ 76	76	54	30
Deferred Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based liabilities paid		9	4	6
Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based liabilities paid		$ 1	$ 0	$ 1

Variable Interest Entities (Det

Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)
Variable Interest Entity [Line Items]
Lease payments after tax	$ 14
Future minimum lease payments before tax	$ 126
Period over which lease payments will be paid	10 years

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - 12 months ended Dec. 31, 2020 $ in Millions, $ in Millions	CAD ($)claim	USD ($)claim
Commitments and Contingencies [Line Items]
Estimated future purchase commitment, next 5 years	$ 1,600
Minimum
Commitments and Contingencies [Line Items]
Period for which future capital and operating expenditures are committed	2021	2021
Maximum
Commitments and Contingencies [Line Items]
Period for which future capital and operating expenditures are committed	2032	2032
Lac-Megantic Rail Accident | Claimed damages as a result of derailment
Commitments and Contingencies [Line Items]
Amount to be distributed	$ 440
Lac-Megantic Rail Accident | Quebec Minister of Sustainable Development, Environment, Wildlife and Parks
Commitments and Contingencies [Line Items]
Value of damages sought	95
Lac-Megantic Rail Accident | Attorney General of Quebec
Commitments and Contingencies [Line Items]
Value of damages sought	315
Damages Sought Previously, Value	409
Lac-Megantic Rail Accident | Initial Subrogated Insurers | Subrogated insurance claim
Commitments and Contingencies [Line Items]
Value of damages sought	15
Damages Sought Previously, Value	$ 16
Number of subrogated insurer claims | claim	8
Lac-Megantic Rail Accident | Additional Subrogated Insurers | Subrogated insurance claim
Commitments and Contingencies [Line Items]
Value of damages sought	$ 3
Number of subrogated insurer claims | claim	2
Lac-Megantic Rail Accident | Class Action Plaintiffs
Commitments and Contingencies [Line Items]
Value of damages sought		$ 5
Number of plaintiffs | claim	48	48
Lac-Megantic Rail Accident | MMAR Estate Representative | Damages for loss in business value
Commitments and Contingencies [Line Items]
Value of damages sought		$ 30
Lac-Megantic Rail Accident | WD Trustee | Damaged railcars and lost crude recovery
Commitments and Contingencies [Line Items]
Value of damages sought		6
Lac-Megantic Rail Accident | WD Trustee | Reimbursement for settlement paid by consignor
Commitments and Contingencies [Line Items]
Value of damages sought		110
Lac-Megantic Rail Accident | WD Trustee | Reimbursement for settlement paid by consignee
Commitments and Contingencies [Line Items]
Value of damages sought		$ 60
Capital Expenditures
Commitments and Contingencies [Line Items]
Future committed expenditures	$ 547
Operating Expenditures
Commitments and Contingencies [Line Items]
Future committed expenditures	$ 1,700

Guarantees (Details)

Guarantees (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Guarantees [Abstract]
Accrued guarantees	$ 18	$ 10

Segmented and Geographic Info_3

Segmented and Geographic Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2020segment
Segment Reporting [Abstract]
Number of operating segments	1

Segmented and Geographic Info_4

Segmented and Geographic Information - Geographic Information (Details) - CAD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 2,012	$ 1,863	$ 1,792	$ 2,043	$ 2,069	$ 1,979	$ 1,977	$ 1,767	$ 7,710	$ 7,792	$ 7,316
Long-term assets excluding financial instruments and pension assets	21,423				20,151				21,423	20,151	18,892
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									5,829	5,675	5,232
Long-term assets excluding financial instruments and pension assets	14,258				13,131				14,258	13,131	12,133
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									1,881	2,117	2,084
Long-term assets excluding financial instruments and pension assets	$ 7,165				$ 7,020				$ 7,165	$ 7,020	$ 6,759

Selected Quarterly Data (Unau_3

Selected Quarterly Data (Unaudited) (Details) - CAD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 2,012	$ 1,863	$ 1,792	$ 2,043	$ 2,069	$ 1,979	$ 1,977	$ 1,767	$ 7,710	$ 7,792	$ 7,316
Operating income	928	779	770	834	890	869	822	543	3,311	3,124	2,831
Net income	$ 802	$ 598	$ 635	$ 409	$ 664	$ 618	$ 724	$ 434	$ 2,444	$ 2,440	$ 1,951
Basic earnings per share	$ 5.97	$ 4.42	$ 4.68	$ 2.99	$ 4.84	$ 4.47	$ 5.19	$ 3.10	$ 18.05	$ 17.58	$ 13.65
Diluted earnings per share	$ 5.95	$ 4.41	$ 4.66	$ 2.98	$ 4.82	$ 4.46	$ 5.17	$ 3.09	$ 17.97	$ 17.52	$ 13.61

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accruals for personal injury and other claims provision
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	$ 141	$ 152	$ 118
Additions charged to expenses	105	142	93
Payments and other reductions	(119)	(152)	(60)
Impact of FX	(1)	(1)	1
Ending balance at December 31	126	141	152
Environmental liabilities
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	77	82	78
Additions charged to expenses	10	6	6
Payments and other reductions	(6)	(8)	(7)
Impact of FX	(1)	(3)	5
Ending balance at December 31	$ 80	$ 77	$ 82

Uncategorized Items - cp-202012

Label	Element	Value
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	$ (5,000,000)
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	(5,000,000)
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	$ (1,000,000)