Note 11 - Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Note 11 - Derivative Instruments (Details) [Line Items]
Derivative, Gain on Derivative	$ 7.2
Unsettled Concentrate Sales Contracts [Member]
Note 11 - Derivative Instruments (Details) [Line Items]
Derivative Asset, Current	0.2
Derivative Liability, Current	0.2
Derivative, Gain on Derivative	2.8
Forecasted Future Concentrate Contracts [Member]
Note 11 - Derivative Instruments (Details) [Line Items]
Derivative Asset, Current	9.8
Derivative Liability, Current	0.3
Derivative, Gain on Derivative	28.1
Derivative Asset, Noncurrent	$ 14.6

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details