Note 8 - Stockholders' Equity - Nonvested Share Activity (Details)	3 Months Ended
	Sep. 30, 2019 $ / shares shares
Nonvested (in shares) | shares
Nonvested, weighted-average grant-date fair value (in dollars per share) | $ / shares
Granted, options (in shares) | shares
Granted, weighted-average grant-date fair value (in dollars per share) | $ / shares
Vested (in shares) | shares
Vested, weighted-average grant-date fair value (in dollars per share) | $ / shares
Nonvested (in shares) | shares
Nonvested, weighted-average grant-date fair value (in dollars per share) | $ / shares