Note 2 - Significant Accounting Policies - Earnings Per Share, Basic and Diluted (Details) - shares	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Shares issued – beginning of period (in shares)	25,327,394		25,327,394		25,011,939	24,748,213	23,784,363	23,573,057
Shares held by subsidiaries (Note 7) (in shares)					(704,309)	(704,309)	(704,309)	(704,309)
Shares outstanding – beginning of period (in shares)	24,623,085		24,623,085		24,307,630	24,043,904	23,080,054	22,868,748
Weighted average shares for fully vested stock bonuses (in shares)				289,051
Weighted average shares issued during the period (in shares)	158,184	268,927	209,903	249,827
Basic weighted average shares – end of period (in shares)	24,465,814	23,348,981	24,253,807	23,407,626