Note 4 - Stock-based Compensation (Details Textual) - USD ($)	6 Months Ended	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
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
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		20,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		6 years 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value		$ 100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		20,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		0	0	0
Employee Stock Option [Member] | Employee Stock Purchase Plan ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		2 years
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent		85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	500,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum		40.06%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum		42.03%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum		0.75%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum		0.77%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term		2 years
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		73,367
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		40,200	39,500	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 15.11	$ 17.49
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		9,067	2,733
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value		$ 900,000	$ 800,000
The 2012 Stock Incentive Plan [Member] | Total Unrecognized Compensation Including Portion Relating to Grants Not Expected to Be Awarded [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		1,000,000
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		$ 700,000
The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		63,915	54,307	75,388	88,728
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		391,600
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		0	0	0
Allocated Share-based Compensation Expense		$ 214,000	$ 146,000	$ 54,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 300,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		1 year 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		52,836	35,208	43,643
Employee Stock Purchase Plan ESPP [Member]
Allocated Share-based Compensation Expense		$ 143,065	$ 139,006	$ 138,677
The 2013 ESOP [Member]
Allocated Share-based Compensation Expense		$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		500,000