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The minimum average realized silver price per ounce that must be met for the silver-price-linked component of dividends to be declared.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The amount of cash paid for brokerage fees during the current period. This element is intended to represent the brokerage fees paid by and between financial industry participants.

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Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Number of share instruments newly issued under a share-based compensation plan.

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Price of a single share of a number of saleable stocks of a company.

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Percentage of vesting of share-based compensation awards.

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For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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Number of new stock issued during the period.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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Note 8 - Shareholders' Equity (Details Textual) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended		6 Months Ended
	Aug. 03, 2017 USD ($) $ / shares	Jun. 30, 2017 USD ($) $ / oz shares	Mar. 31, 2017 USD ($) shares	Jun. 30, 2017 USD ($) $ / shares $ / oz shares	Jun. 30, 2016 $ / shares	Jun. 30, 2017 USD ($) $ / shares $ / oz shares	Jun. 30, 2016 USD ($) $ / shares shares	Aug. 01, 2017 $ / shares	Feb. 23, 2016 USD ($)	May 08, 2012 shares
Share-based Compensation Arrangement by Share-based Payment Award, Measurement Period Used to Value Performance-based Awards		3 years
Average Realized Silver Price \| $ / oz				17.14
Average Realized Silver Price Minimum Dividend Threshold \| $ / oz		30		30		30
Stock Issued During Period, Shares, New Issues \| shares				1,828,760		4,608,847
Stock Issued During Period, Value, New Issues				$ 9,600		$ 17,700
Payments for Brokerage Fees				$ 196		$ 362
Shares Paid for Tax Withholding for Share Based Compensation \| shares						488,634	997,678
Payments Related to Tax Withholding for Share-based Compensation						$ 2,500	$ 3,400
Treasury Stock Acquired, Average Cost Per Share \| $ / shares						$ 5.06	$ 3.40
Common Stock, Dividends, Per Share, Declared \| $ / shares				$ 0.0025	$ 0.0025	$ 0.005	$ 0.005
Common Stock Repurchase Program [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased \| shares										20,000,000
Cumulative Stock Repurchased \| shares		934,100		934,100		934,100
Treasury Stock Acquired, Average Cost Per Share \| $ / shares						$ 3.99
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased \| shares		19,100,000		19,100,000		19,100,000
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared \| $ / shares	$ 0.0025
Dividends, Common Stock	$ 1,000
Subsequent Event [Member] \| Common Stock Repurchase Program [Member]
Share Price \| $ / shares								$ 5.54
Minimum [Member]
Common Stock, Dividends, Per Share, Declared \| $ / shares						$ 0.01
Maximum [Member]
Common Stock, Aggregate Offering Price									$ 75,000
Employees and Non-employee Directors [Member]
Allocated Share-based Compensation Expense						$ 2,800	$ 3,500
Restricted Stock Units (RSUs) Vesting in June 2018, 2019, and 2020 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares		775,379
Restricted Stock Units (RSUs) Vesting in June 2018, 2019, and 2020 [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.00%
Restricted Stock Units (RSUs) Vesting in June 2018, 2019, and 2020 [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.00%
Restricted Stock Units (RSUs) Vesting in June 2018, 2019, and 2020 [Member] \| Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.00%
Restricted Stock Units (RSUs) Vesting in June 2018 and 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares		93,691
Restricted Stock Units (RSUs) Vesting in June 2018 and 2019 [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
Restricted Stock Units (RSUs) Vesting in June 2018 and 2019 [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
Restricted Stock Units (RSUs) Vesting in June 2018 [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 1,900		$ 1,900		1,900
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		1 year
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares		15,336
Restricted Stock Units (RSUs) Vesting in June 2019 [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 1,800		1,800		1,800
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years
Restricted Stock Units (RSUs) Vesting in June 2020 [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 1,500		$ 1,500		$ 1,500
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		3 years
Performance Shares [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 180 days
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period \| shares			641,406
Allocated Share-based Compensation Expense			$ 4,200