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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

+ References

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

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or per unit amount of equity securities issued.

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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Note 3 - Accounting for Stock-based Compensation (Details Textual) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
2006 Employee Equity Compensation Restricted Stock Plan (the "Employee Plan") [Member] \| Restricted Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross				976,461
2016 Employee Equity Compensation Restricted Stock Plan [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross	49,200
Shares Issued, Price Per Share	$ 48.37
2016 Employee Equity Compensation Restricted Stock Plan [Member] \| Restricted Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross				49,200
2006 Outside Director Equity Compensation Restricted Stock Plan (the "Director Plan") [Member] \| Restricted Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross				272,000
2015 Outside Director Equity Compensation Restricted Stock Plan ("2015 Director Plan") [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross	30,000
Shares Issued, Price Per Share	$ 48.37
2015 Outside Director Equity Compensation Restricted Stock Plan ("2015 Director Plan") [Member] \| Restricted Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross				60,000
Employee and Director Plans [Member] \| Restricted Stock [Member]
Allocated Share-based Compensation Expense		$ 652,000	$ 483,000	$ 1,100,000	$ 946,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition				3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		236,000	273,000	236,000	273,000
Employee and Director Plans [Member] \| Restricted Stock [Member] \| General and Administrative Expense [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 6,000,000	$ 4,300,000	$ 6,000,000	$ 4,300,000