Note 10 - Equity Compensation - Stock Options (Details) - USD ($)	6 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Outstanding (in shares)	3,119,688			2,976,490
Outstanding (in dollars per share)	$ 9.12			$ 8.97
Outstanding (Year)	7 years 146 days	7 years 36 days	7 years 146 days	6 years 219 days
Outstanding	$ 971,344	$ 4,648,729	$ 2,332,224	$ 8,338,974
Granted (in shares)	794,537	834,320
Granted (in dollars per share)	$ 5.98	$ 11.05
Forfeitures (in shares)	(438,609)	(147,375)
Forfeitures (in dollars per share)	$ 11.62	$ 16.03
Exercised (in shares)	(26,939)	(38,063)
Exercised (in dollars per share)	$ 6.49	$ 7.75
Outstanding (in shares)	3,448,677	3,625,372	3,119,688
Outstanding (in dollars per share)	$ 8.10	$ 9.18	$ 9.12
Exercisable (in shares)	1,527,651	1,700,025
Exercisable (in dollars per share)	$ 8.14	$ 8.73
Exercisable (Year)	5 years 255 days	5 years 36 days
Exercisable	$ 218,246	$ 3,216,899
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 146 days	7 years 36 days	7 years 146 days	6 years 219 days
Outstanding	$ 971,344	$ 4,648,729	$ 2,332,224	$ 8,338,974
Forfeitures (in shares)	(438,609)	(147,375)
Forfeitures (in dollars per share)	$ 11.62	$ 16.03
Exercised (in shares)	(26,939)	(38,063)
Exercised (in dollars per share)	$ 6.49	$ 7.75