The estimated statutory income tax rate in the specified fiscal year.

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Aggregate number of common shares reserved for future issuance.

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Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

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Unrecognized cost of unvested share-based compensation awards.

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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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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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The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Note 12 - Employee Equity Incentive Plans (Details Textual) - USD ($)	9 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2016	Aug. 26, 2016	Aug. 30, 2013	Sep. 16, 2011	Sep. 10, 2009
Estimated Statutory Income Tax Rate	40.00%	35.00%
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 7,400,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 292 days
RadioPulse [Member]
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards		$ 249,000	$ 249,000
Plan 2009 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized							900,000
Plan 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized						600,000
Plan 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					2,000,000
Plan 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				2,000,000
Stock Options of Plans Two Thousand and Nine Two Thousand and Eleven Two Thousand and Thirteen and Two Thousand and Sixteen [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Stock Options of Plans Two Thousand and Nine Two Thousand and Eleven Two Thousand and Thirteen and Two Thousand and Sixteen [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	100.00%
Stock Appreciation Rights of Plans Two Thousand and Nine Two Thousand and Eleven Two Thousand and Thirteen and Two Thousand and Sixteen [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	100.00%
Stock Appreciation Rights of Plans Two Thousand and Nine Two Thousand and Eleven Two Thousand and Thirteen and Two Thousand and Sixteen [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Employee Stock Purchase Plan 1999 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1,550,000
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	15.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans	112,171
Common Stock, Capital Shares Reserved for Future Issuance	128,070