Note 10 - Stock-based Compensation (Details Textual) - USD ($)
|
|
12 Months Ended |
|
|
|
Feb. 27, 2013 |
Mar. 31, 2017 |
Mar. 31, 2016 |
Mar. 31, 2015 |
Mar. 31, 2014 |
Sep. 23, 2010 |
Dec. 08, 2006 |
| Share-based Compensation Arrangements by Share-based Payment Award Exercise Price of Option Granted as Percentage of Bid Price of Underlying Shares |
|
100.00%
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |
|
510,361
|
515,720
|
437,248
|
398,172
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value |
|
$ 7,574,945
|
$ 5,260,000
|
$ 3,546,000
|
|
|
|
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized |
|
$ 5,906,075
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant |
|
822,781
|
|
|
|
|
|
| The 2014 Plan [Member] |
|
|
|
|
|
|
|
| Common Stock, Capital Shares Reserved for Future Issuance |
|
1,100,000
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |
|
270,219
|
|
|
|
|
|
| The 2006 Plan [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |
|
240,142
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |
|
|
|
|
|
800,000
|
400,000
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized |
400,000
|
|
|
|
|
|
|
| Minimum [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |
|
4 years
|
|
|
|
|
|
| Maximum [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |
|
7 years
|
|
|
|
|
|
| Employee Stock Option [Member] | Minimum [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period |
|
5 years
|
|
|
|
|
|
| Employee Stock Option [Member] | Maximum [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period |
|
10 years
|
|
|
|
|
|
| Restricted Stock [Member] | The 2014 Plan [Member] |
|
|
|
|
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period |
|
7,000
|
|
|
|
|
|