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v3.19.1

Property, plant and equipment (Narrative) (Details) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2017 CAD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2018 CAD ($) | Dec. 31, 2017 CAD ($) | Dec. 31, 2017 USD ($)
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Contracutal capital commitments |  |  | $ 16,000,000 |  |
Impairment charges |  |  | 0 | $ 358,330,000 |
Uranium [Member] |  |  |  |  |
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Impairment charges |  |  | $ 0 | 246,931,000 |
Uranium [Member] | Inkai [Member] |  |  |  |  |
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Ownership interest in JV Inkai |  |  | 40.00% |  |
Uranium [Member] | US operations [Member] |  |  |  |  |
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Impairment charges | $ 184,448,000 | $ 144,450,000 |  |  |
Uranium [Member] | McArthur River, Key Lake operations [Member] |  |  |  |  |
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Impairment charges | 55,333,000 |  |  |  |
Uranium [Member] | Non-recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | US operations [Member] |  |  |  |  |
Disclosure Of Property Plant And Equipment [Line Items] |  |  |  |  |
Recoverable amount | $ 133,228,000 |  |  | $ 133,228,000 | $ 106,200,000

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