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, 2021	Jun. 30, 2020
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)	5,298,282	4,774,582
Stock option activity, shares [Roll Forward]
Number of options outstanding at beginning of year (in shares)	1,765,100	1,711,600
Options granted (in shares)	523,700	614,700
Options forfeited (in shares)	0	(7,000)
Options paid in cash upon vesting (in shares)	(781,200)	(554,200)
Number of options outstanding at period end (in shares)	1,507,600	1,765,100
Stock option related information [Abstract]
Cash paid out on options vested	$ 3,920	$ 2,516
Compensation expense recognized	4,012	3,280
Total liability for the Plan	$ 5,000	$ 4,900
Minimum [Member]
Share-based Compensation [Abstract]
Strike price of phantom stock options as percent of book value	100.00%