Write-Downs (Notes)	12 Months Ended
Dec. 31, 2020
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Asset Impairment Charges [Text Block]	IMPAIRMENT OF LONG-LIVED ASSETSIn 2019, the Company performed a comprehensive analysis of its Silvertip property and determined that indicators of impairment existed, primarily as a result of further deterioration in zinc and lead market conditions as well as processing facility-related challenges. As a result, a non-cash impairment charge of $250.8 million was recorded during the in 2019. The write-down was allocated between Property, plant and equipment, net, Mining properties, net and Other non-current assets, $43.6 million, $201.5 million and $5.7 million, respectively. See Note 16 -- Fair Value Measurements for additional detail of the assumptions used in the determination of the fair value of the long-lived assets tested for impairment.

Write-Downs (Notes)

12 Months Ended

Dec. 31, 2020

Impairment or Disposal of Tangible Assets Disclosure [Abstract]

IMPAIRMENT OF LONG-LIVED ASSETSIn 2019, the Company performed a comprehensive analysis of its Silvertip property and determined that indicators of impairment existed, primarily as a result of further deterioration in zinc and lead market conditions as well as processing facility-related challenges. As a result, a non-cash impairment charge of $250.8 million was recorded during the in 2019. The write-down was allocated between Property, plant and equipment, net, Mining properties, net and Other non-current assets, $43.6 million, $201.5 million and $5.7 million, respectively. See Note 16 -- Fair Value Measurements for additional detail of the assumptions used in the determination of the fair value of the long-lived assets tested for impairment.