Note 9 - Stockholders' Equity (Detail) - Options outstanding and exercisable, by exercise range (USD $)	12 Months Ended
	Mar. 31, 2013
Options Outstanding, Number of Shares (in Shares)	161,000
Range One [Member]
Options Outstanding, Number of Shares (in Shares)	28,000
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	4 years 116 days
Options Vested and Exercisable, Number of Shares (in Shares)	15,906
Options Vested and Exercisable,	$ 4.63
Range One [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 3.70
Range One [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 5.18
Range Two [Member]
Options Outstanding, Number of Shares (in Shares)	32,973
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	7 years 299 days
Options Vested and Exercisable, Number of Shares (in Shares)	18,591
Options Vested and Exercisable,	$ 5.20
Range Two [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 5.20
Range Two [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 5.20
Range Three [Member]
Options Outstanding, Number of Shares (in Shares)	46,355
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	6 years 339 days
Options Vested and Exercisable, Number of Shares (in Shares)	23,547
Options Vested and Exercisable,	$ 5.33
Range Three [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 5.26
Range Three [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 5.39
Range Four [Member]
Options Outstanding, Number of Shares (in Shares)	34,902
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	6 years 171 days
Options Vested and Exercisable, Number of Shares (in Shares)	28,191
Options Vested and Exercisable,	$ 7.44
Range Four [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 5.40
Range Four [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 11.40
Range Five [Member]
Options Outstanding, Number of Shares (in Shares)	18,970
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	2 years 219 days
Options Vested and Exercisable, Number of Shares (in Shares)	18,970
Options Vested and Exercisable,	$ 24.14
Range Five [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 14.50
Range Five [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 42.40
Range Six [Member]
Options Outstanding, Number of Shares (in Shares)	161,200
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	6 years 18 days
Options Vested and Exercisable, Number of Shares (in Shares)	105,565
Options Vested and Exercisable,	$ 9.15
Range Six [Member] | Minimum [Member]
Range of Exercise Prices Per Share - Minimum	$ 3.70
Range Six [Member] | Maximum [Member]
Range of Exercise Prices Per Share - Maximum	$ 42.40