Note 11 - Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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

March 31, 2014	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
2014 settlements		1,590		7		29,817		9,755	$	20.15	$	1,304	$	0.91	$	0.95
Contracts on forecasted sales
2014 settlements		—		—		29,652		21,054	N/A		N/A		$	0.99	$	1.05
2015 settlements		—		—		45,635		40,179	N/A		N/A		$	0.96	$	1.07
2016 settlements		—		—		9,094		31,030	N/A		N/A		$	0.94	$	1.03

	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
2014 settlements		673		3		11,188		3,472	$	19.50	$	1,205	$	0.89	$	1.00
Contracts on forecasted sales
2014 settlements		—		—		31,967		34,282	N/A		N/A		$	1.00	$	1.04
2015 settlements		—		—		39,683		36,982	N/A		N/A		$	0.96	$	1.07
2016 settlements		—		—		3,803		30,589	N/A		N/A		$	0.96	$	1.03