Note 3 - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017	Sep. 05, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)					500,000
The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	119,533
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)	2 years 182 days
Share-based Payment Arrangement, Expense	$ 345,000	$ 232,000	$ 134,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	2 years 36 days
Employee Stock Purchase Plan ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	99,193	87,133	70,515	77,285
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	86,946	55,227	63,607
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (in shares)	54,271	26,628	52,816
Share-based Payment Arrangement, Expense	$ 100,000	$ 100,000	$ 100,000
The 2013 ESOP [Member]
Share-based Payment Arrangement, Expense	$ 0	$ 0	$ 0
Share-based Payment Arrangement, Option [Member] | The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	20,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	0	0	0
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 (in shares)	20,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (in shares)	0
Share-based Payment Arrangement, Option [Member] | Employee Stock Purchase Plan ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in shares)	0
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, Fair Value Assumptions, Expected Volatility Rate, Minimum	46.72%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	48.95%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	0.17%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum	1.66%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)	2 years
Restricted Stock Units (RSUs) [Member] | The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	242,840
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	110,500	67,000	62,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 5.34	$ 6.34	$ 7.22
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)	64,661	10,800
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 800,000	$ 1,300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	2,000,000
Portion Relating to RSU Grants Not Expected to be Awarded [Member] | The 2012 Stock Incentive Plan [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 1,700,000
Minimum [Member] | Share-based Payment Arrangement, Option [Member] | The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	1 year
Minimum [Member] | Share-based Payment Arrangement, Option [Member] | Employee Stock Purchase Plan ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
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 (Year)	1 year
Maximum [Member] | Share-based Payment Arrangement, Option [Member] | The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	3 years
Maximum [Member] | Share-based Payment Arrangement, Option [Member] | Employee Stock Purchase Plan ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
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 (Year)	3 years