Note 5 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Thousands, $ in Millions | 3 Months Ended | |
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 05, 2012 |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | | | 500,000 |
The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 230,033 | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total | $ 0.5 | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 109 days | | |
The 2012 Stock Incentive Plan [Member] | Portion Relating to RSU Grants Not Expected to be Awarded [Member] | | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total | $ 1.4 | | |
Employee Stock Option [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | 10 years | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance | 20,000 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | 0 | 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 4 years 91 days | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0.1 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 20,000 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period | 0 | | |
Restricted Stock Units (RSUs) [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number, Ending Balance | 199,502 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 1.2 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 67,000 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ 6,340 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period | 8,300 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period | 0 | | |
Allocated Share-based Compensation Expense, Total | $ 0.1 | $ 0.1 | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total | $ 1.9 | | |
Minimum [Member] | Employee Stock Option [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 1 year | | |
Minimum [Member] | Restricted Stock Units (RSUs) [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 1 year | | |
Maximum [Member] | Employee Stock Option [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 3 years | | |
Maximum [Member] | Restricted Stock Units (RSUs) [Member] | The 2012 Stock Incentive Plan [Member] | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 3 years | | |