XML 190 R124.htm IDEA: XBRL DOCUMENT v3.20.1
Segmented information - Major customers (Details) - CAD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Disclosure of major customers [line items]    
Revenue $ 1,862,925,000 $ 2,091,661,000
One customer of Cameco's uranium and fuel services segments [member]    
Disclosure of major customers [line items]    
Revenue $ 422,740,000 $ 204,594,000
Percentage of entity's revenue 24.00% 10.00%
Information about major customers As customers are relatively few in number, accounts receivable from any individual customer may periodically exceed 10% of accounts receivable depending on delivery schedule.