Stock-Based Compensation, Phantom Stock Option Plan and Long-term Incentive Plan (Details) - 2011 Phantom Stock Option and Long-term Incentive Plan [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2019
Stock option activity, shares [Roll Forward]
Number of options outstanding, beginning of period (in shares)	1,765,100	1,742,100	1,711,600	1,634,160
Options Granted (in shares)	0	0	614,700	592,700
Options Forfeited (in shares)	0	0	(7,000)	0
Options Paid in Cash (in shares)	0	(18,000)	(554,200)	(502,760)
Number of options outstanding, end of period (in shares)	1,765,100	1,724,100	1,765,100	1,724,100
Stock option related information [Abstract]
Cash paid out on options vested	$ 0	$ 41	$ 2,516	$ 1,745
Compensation costs recognized	875	$ 810	2,270	$ 2,021
Total liability for the Plan	$ 3,900		$ 3,900		$ 4,100