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Segmented information - Narrative (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Operating Segments [Line Items]
Segment information	Cameco has two reportable segments: uranium and fuel services. Cameco's reportable segments are strategic business units with different products, processes and marketing strategies.
Uranium [Member]
Disclosure Of Operating Segments [Line Items]
Care and maintenance	$ 195,972,000	$ 153,924,000
Uranium [Member] | Cigar Lake [Member]
Disclosure Of Operating Segments [Line Items]
COVID-19 care and maintenance	45,988,000
Fuel Service [Member]
Disclosure Of Operating Segments [Line Items]
COVID-19 care and maintenance	$ 8,992,000

X

- Definition

Costs directly expensed to cost of sales that are incurred to maintain production facilities during suspension of production.

+ References

No definition available.

+ Details

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X

- Definition

Costs directly expensed to cost of sales that are incurred to maintain production facilities during a COVID-19 suspension of production.

+ References

No definition available.

+ Details

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X

- 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.

+ Details

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- Definition

The description of the factors used to identify the entity's reportable segments, including the basis of organisation (for example, whether management has chosen to organise the entity around differences in products and services, geographical areas, regulatory environments or a combination of factors and whether operating segments have been aggregated). [Refer: Geographical areas [member]; Operating segments [member]; Products and services [member]; Reportable segments [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2020-01-01
-Paragraph 22
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_22_a&doctype=Standard
-URIDate 2020-01-01

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- Details

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- Details

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