Note 10 - Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block]

	December 31,
Balance sheet line item:	2021		2020
Other current assets	$	2.7	$	3.5
Other non-current assets		2.5		4.2

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

December 31, 2021	Ounces/pounds under contract (in 000's)								Average price per ounce/pound
	Silver		Gold		Zinc		Lead		Silver		Gold		Zinc		Lead
	(ounces)		(ounces)		(pounds)		(pounds)		(ounces)		(ounces)		(pounds)		(pounds)
Contracts on provisional sales
2022 settlements		1,814		6		13,371		4,575	$	23.02	$	1,812	$	1.39	$	0.96
Contracts on forecasted sales
2022 settlements		—		—		57,706		59,194		N/A		N/A	$	1.28	$	0.98
2023 settlements		—		—		76,280		71,650		N/A		N/A	$	1.29	$	1.00

December 31, 2020	Ounces/pounds under contract (in 000's)								Average price per ounce/pound
	Silver		Gold		Zinc		Lead		Silver		Gold		Zinc		Lead
	(ounces)		(ounces)		(pounds)		(pounds)		(ounces)		(ounces)		(pounds)		(pounds)
Contracts on provisional sales
2022 settlements		1,282		4		23,314		4,905	$	25.00	$	1,858	$	1.19	$	0.90
Contracts on forecasted sales
2022 settlements		—		—		41,577		30,876		N/A		N/A	$	1.17	$	0.88
2023 settlements		N/A		N/A		18,519		—		N/A		N/A	$	1.28		N/A

Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block]

	December 31, 2021								December 31, 2020
Balance sheet line item:	Contracts in an asset position		Contracts in a liability position			Net asset (liability)			Contracts in an asset position		Contracts in a liability position			Net asset (liability)
Other current assets	$	—	$	—		$	—		$	0.2	$	(0.2	)	$	—
Other non-current assets		—		—			—			0.5		(0.1	)		0.4
Current derivatives liability		0.7		(20.1	)		(19.4	)		0.1		(11.8	)		(11.7	)
Non-current derivatives liability		0.4		(18.9	)		(18.5	)		—		—			—