Percentage change in interest rate.

No definition available.

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- Definition

Proportion of outstanding debt with fixed rate.

+ References

No definition available.

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- Definition

Quoted market yields.

+ References

No definition available.

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- Definition

The adjustment to the basis (reference rate) used for calculation of the interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
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- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

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- Definition

The basis (reference rate) used for calculation of the interest rate on borrowings. [Refer: Borrowings]

+ References

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- Definition

The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

+ References

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

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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- Definition

The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

+ References

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- Definition

The amount of financial assets that the entity has pledged as collateral for liabilities or contingent liabilities, including amounts that have been reclassified in accordance with paragraph 3.2.23(a) of IFRS 9. [Refer: Contingent liabilities [member]; Financial assets]

+ References

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- Definition

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The amount of short-term deposits held by the entity that are not classified as cash equivalents. [Refer: Cash equivalents]

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Financial instruments - Narrative (Details) - CAD ($)	12 Months Ended
Financial instruments - Narrative (Details) - CAD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about financial instruments [line items]
Gain (loss)	$ 32,269,000	$ (81,081,000)
Cash and cash equivalents	1,062,431,000	711,528,000	$ 591,620,000
Short-term investments	0	$ 391,025,000
Pledged cash as security	$ 195,729,000
Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Quoted market yields	1.70%	1.90%
Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Quoted market yields	1.80%	2.20%
Interest rate swap contracts [member]
Disclosure of detailed information about financial instruments [line items]
Gain (loss)	$ 2,068,000	$ 2,032,000
Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	1,062,431,000	711,528,000
Short-term investments	$ 0	$ 391,025,000
Interest rate risk [member]
Disclosure of detailed information about financial instruments [line items]
Proportion of outstanding debt that carries fixed rate	85.00%	67.00%
Interest rate risk [member] \| Interest rate swap contracts [member]
Disclosure of detailed information about financial instruments [line items]
Percentage increase in interest rate	1.00%
Gain (loss)	$ 1,524,000
Fair value of Cameco's interest rate swap assets	2,313,000	$ 856,000
Interest rate risk [member] \| Interest rate swap contracts [member] \| Series E senior unsecured debenture [Member]
Disclosure of detailed information about financial instruments [line items]
Notional amount	$ 150,000,000
Interest rate risk [member] \| Interest rate swap contracts [member] \| Series E senior unsecured debenture [Member] \| Floating interest rate [member]
Disclosure of detailed information about financial instruments [line items]
Interest rate basis	the three-month Canada Dealer Offered Rate
Margin rate	1.20%
Interest rate risk [member] \| Interest rate swap contracts [member] \| Series E senior unsecured debenture [Member] \| Fixed interest rate [member]
Disclosure of detailed information about financial instruments [line items]
Interest rate	3.75%