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v3.21.1

Management of Financial Risk (Disclosure of Nature and Extent Arising from Financial Instruments - Commodity Price Risk) (Details) $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 USD ($) $ / T | Dec. 31, 2019 USD ($) | Feb. 11, 2021 $ / T | Dec. 31, 2020 $ / gal | Dec. 31, 2020 | Dec. 31, 2020 USD ($)
Entering in to Derivative Contract [Member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate quantity of zero cost collars |  |  | 6,237 |  |  |
Floor Price | $ / T |  |  | 2,000 |  |  |
Cap Price | $ / T |  |  | 2,125 |  |  |
Silver Commodity Type [member] | Commodity price risk [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Effect on Sales | $ 1,338 |  |  |  |  |
Change percentage, commodity | (10.00%) |  |  |  |  |
Gold Commodity Type [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Increase (decrease) in sales due to price changes of commodity | $ 3,307 | $ 368 |  |  |  |
Gold Commodity Type [member] | Commodity price risk [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Effect on Sales | $ 561 |  |  |  |  |
Change percentage, commodity | (10.00%) |  |  |  |  |
Lead Commodity [member] | Commodity price risk [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Effect on Sales | $ 195 |  |  |  |  |
Change percentage, commodity | (10.00%) |  |  |  |  |
Zinc Commodity [member] | Entering in to Derivative Contract [Member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate quantity of zero cost collars |  |  |  |  | 12,300 |
Floor Price | $ / T | 2,600 |  |  |  |  |
Cap Price | $ / T | 2,900 |  |  |  |  |
Zinc Commodity [member] | Commodity price risk [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Effect on Sales | $ 253 |  |  |  |  |
Change percentage, commodity | (10.00%) |  |  |  |  |
Heating Oil Commodity [Member] | Entering in to Derivative Contract [Member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate quantity of zero cost collars |  |  |  |  | 720,000 |
Floor Price | $ / gal |  |  |  | 1.40 |  |
Cap Price | $ / gal |  |  |  | 1.6150 |  |
Heating Oil Commodity [Member] | Entering in to Derivative Contract [Member] | Swap contract [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate forward- swap |  |  |  | 1.52 | 720,000 |
Jet Fuel Commodity [Member] | Entering in to Derivative Contract [Member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate quantity of zero cost collars |  |  |  |  | 1,680,000 |
Floor Price | $ / gal |  |  |  | 1.30 |  |
Cap Price | $ / gal |  |  |  | 1.4775 |  |
Jet Fuel Commodity [Member] | Entering in to Derivative Contract [Member] | Swap contract [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Aggregate forward- swap |  |  |  | 1.438 | 1,680,000 |
Non-Revolving Credit Facility [Member] | Interest rate risk [member] |  |  |  |  |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |  |  |  |  |
Borrowing capacity |  |  |  |  |  | $ 40,000

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