Note 14 - Quarterly Financial Information (Unaudited) (Detail) - Quarterly Financial Information (USD $)	12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
2013
Operating Revenues	$ 103,064,239		$ 89,382,131
Operating Income	2,728,028		2,073,540
Net Income	1,669,860		1,350,224
Basic Earnings per share (in Dollars per share)	$ 0.68		$ 0.55
Diluted Earnings per share (in Dollars per share)	$ 0.68		$ 0.55
First [Member]
2013
Operating Revenues	24,488,000		16,561,000
Operating Income	654,000		251,000
Net Income	417,000	[1]	168,000
Basic Earnings per share (in Dollars per share)	$ 0.17		$ 0.07
Diluted Earnings per share (in Dollars per share)	$ 0.17		$ 0.07
Second [Member]
2013
Operating Revenues	21,162,000		25,461,000
Operating Income	351,000		919,000
Net Income	227,000	[1]	593,000
Basic Earnings per share (in Dollars per share)	$ 0.09		$ 0.24
Diluted Earnings per share (in Dollars per share)	$ 0.09		$ 0.24
Third [Member]
2013
Operating Revenues	26,703,000		25,650,000
Operating Income	986,000		901,000
Net Income	633,000	[1]	579,000
Basic Earnings per share (in Dollars per share)	$ 0.26		$ 0.24
Diluted Earnings per share (in Dollars per share)	$ 0.26		$ 0.24
Fourth [Member]
2013
Operating Revenues	30,711,000		21,710,000
Operating Income	737,000		2,000
Net Income	$ 393,000	[1]	$ 10,000
Basic Earnings per share (in Dollars per share)	$ 0.16
Diluted Earnings per share (in Dollars per share)	$ 0.16

[1] Adjustments for an over statement of Puerto Rico tax credits and other accumulated items in prior periods resulted in an increase in the provision for income taxes in the Company's fourth quarter.