Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Note 6 - Stock-based Compensation (Details Textual) - shares	1 Months Ended	12 Months Ended
	May 31, 2012	Dec. 31, 2004	Mar. 31, 2018
2004 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		3,750,000
2004 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		2 years
2004 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
2004 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
2004 Stock Incentive Plan [Member] \| Employee Stock Option [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		1 year
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
2012 Stock Incentive Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	6 years
2012 Stock Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	4,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche One [Member] \| Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	100.00%
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche One [Member] \| Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Two [Member] \| Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Three [Member] \| Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
2012 Stock Incentive Plan [Member] \| Stock Options And Stock Appreciation Rights [Member] \| Share-based Compensation Award, Tranche Four [Member] \| Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
2012 Stock Incentive Plan [Member] \| Employee Stock Option [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized			5,000,000