Condensed Consolidating Financial Information - Interim Condensed Consolidating Statements of Cash Flows (Details) - CAD CAD in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Cash provided by operating activities	CAD 311	CAD 218
Investing activities
Additions to properties	(230)	(278)
Proceeds from sale of properties and other assets	3	60
Advances to affiliates	0	0
Capital contributions to affiliates	0	0
Repurchase of share capital from affiliates		0
Payments for (Proceeds from) Other Investing Activities	5	0
Cash used in investing activities	(222)	(218)
Financing activities
Dividends paid	(73)	(54)
Issuance of share capital	0	0
Return of share capital to affiliates		0
Issuance of CP Common Shares	28	5
Repayment of long-term debt, excluding commercial paper	(5)	(11)
Advances from affiliates	0	0
Other	0	(2)
Cash used in financing activities	(50)	(62)
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	(2)	(17)
Cash position
(Decrease) increase in cash and cash equivalents	37	(79)
Cash and cash equivalents at beginning of period	164	650
Cash and cash equivalents at end of period	201	571
Consolidating Adjustments and Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by operating activities	(101)	(54)
Investing activities
Additions to properties	0	0
Proceeds from sale of properties and other assets	0	0
Advances to affiliates	286	35
Capital contributions to affiliates	68	9
Repurchase of share capital from affiliates		(6)
Payments for (Proceeds from) Other Investing Activities	0
Cash used in investing activities	354	38
Financing activities
Dividends paid	101	54
Issuance of share capital	(68)	(9)
Return of share capital to affiliates		6
Issuance of CP Common Shares	0	0
Repayment of long-term debt, excluding commercial paper	0	0
Advances from affiliates	(286)	(35)
Other		0
Cash used in financing activities	(253)	16
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	0	0
Cash position
(Decrease) increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
CPRL (Parent Guarantor) [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by operating activities	63	23
Investing activities
Additions to properties	0	0
Proceeds from sale of properties and other assets	0	0
Advances to affiliates	(152)	0
Capital contributions to affiliates	0	0
Repurchase of share capital from affiliates		0
Payments for (Proceeds from) Other Investing Activities	0
Cash used in investing activities	(152)	0
Financing activities
Dividends paid	(73)	(54)
Issuance of share capital	0	0
Return of share capital to affiliates		0
Issuance of CP Common Shares	28	5
Repayment of long-term debt, excluding commercial paper	0	0
Advances from affiliates	134	26
Other		0
Cash used in financing activities	89	(23)
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	0	0
Cash position
(Decrease) increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
CPRC (Subsidiary Issuer) [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by operating activities	85	51
Investing activities
Additions to properties	(109)	(132)
Proceeds from sale of properties and other assets	1	57
Advances to affiliates	0	(35)
Capital contributions to affiliates	(68)	(9)
Repurchase of share capital from affiliates		6
Payments for (Proceeds from) Other Investing Activities	5
Cash used in investing activities	(171)	(113)
Financing activities
Dividends paid	(73)	(54)
Issuance of share capital	0	0
Return of share capital to affiliates		0
Issuance of CP Common Shares	0	0
Repayment of long-term debt, excluding commercial paper	(5)	(4)
Advances from affiliates	149	0
Other		(2)
Cash used in financing activities	71	(60)
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	(2)	(4)
Cash position
(Decrease) increase in cash and cash equivalents	(17)	(126)
Cash and cash equivalents at beginning of period	100	502
Cash and cash equivalents at end of period	83	376
Non-Guarantor Subsidiaries [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by operating activities	264	198
Investing activities
Additions to properties	(121)	(146)
Proceeds from sale of properties and other assets	2	3
Advances to affiliates	(134)	0
Capital contributions to affiliates	0	0
Repurchase of share capital from affiliates		0
Payments for (Proceeds from) Other Investing Activities	0
Cash used in investing activities	(253)	(143)
Financing activities
Dividends paid	(28)	0
Issuance of share capital	68	9
Return of share capital to affiliates		(6)
Issuance of CP Common Shares	0	0
Repayment of long-term debt, excluding commercial paper	0	(7)
Advances from affiliates	3	9
Other		0
Cash used in financing activities	43	5
Effect of foreign currency fluctuations on U.S. dollar-denominated cash and cash equivalents	0	(13)
Cash position
(Decrease) increase in cash and cash equivalents	54	47
Cash and cash equivalents at beginning of period	64	148
Cash and cash equivalents at end of period	CAD 118	CAD 195

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

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Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

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Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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Amount of cash (inflow) outflow from investing activities classified as other.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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The cash outflow associated with the acquisition of or advances to an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, and joint venture or equity method investment) or the acquisition of an additional interest in a subsidiary (controlled entity).

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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The cash outflow associated with extending a long-term loan to a related party. Alternate caption: Payments for Advances to Affiliates.

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The cash inflow associated with the amount received by a corporation from a shareholder during the period.

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The cash inflow from an entity that is affiliated with the entity by means of direct or indirect ownership.

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Cash dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporations that are returns of capital. Excludes dividends or distributions from equity method investments classified as operating activities.

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The cash inflow from the additional capital contribution to the entity.

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The net cash inflow or outflow resulting from the entity's share transaction.

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Amount of cash inflow from the sale of tangible or intangible assets used to produce goods or deliver services, classified as other.

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The cash outflow associated with security instruments that either represent a creditor or an ownership relationship with the holder of the investment security with a maturity of beyond one year or normal operating cycle, if longer. Includes repayments of (a) debt, (b) capital lease obligations, (c) mandatory redeemable capital securities, and (d) any combination of (a), (b), or (c).

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