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	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation [Abstract]
Number of shares authorized under the plan (in shares)	5,800,000	5,800,000
Number of options granted to date (in shares)	4,159,882	3,567,182
Stock option activity, shares [Roll Forward]
Outstanding at beginning of period (in shares)	1,634,160	1,522,720
Options granted (in shares)	592,700	594,200
Options forfeited (in shares)	(12,500)	(27,000)
Options paid in cash upon vesting (in shares)	(502,760)	(455,760)
Outstanding at period end (in shares)	1,711,600	1,634,160
Stock option related information [Abstract]
Cash paid out on options vested	$ 1,745	$ 1,187
Compensation costs recognized	2,901	2,140
Total liability for the Plan	$ 4,100	$ 3,000
Minimum [Member]
Share-based Compensation [Abstract]
Strike price of phantom stock options as percent of book value	100.00%