Note 4 - Fair Value (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Mar. 31, 2015
Other than Temporary Impairment Losses, Investments	$ 454,000	$ 454,000
Auction Rate Preferred Securities Percentage Collateralized	100.00%	100.00%
Collateralized Asset Value Exceeding Value of ARPS Percentage	300.00%	300.00%
Debt, Long-term and Short-term, Combined Amount	$ 53,900,000	$ 53,900,000	$ 49,200,000