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		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2020
Stock option activity, shares [Roll Forward]
Number of options outstanding, beginning of period (in shares)	2,288,800	2,319,300	1,765,100	1,711,600
Options Granted (in shares)	0	0	523,700	614,700
Options Forfeited (in shares)	0	0	0	(7,000)
Options Paid in Cash (in shares)	(583,200)	(554,200)	(583,200)	(554,200)
Number of options outstanding, end of period (in shares)	1,705,600	1,765,100	1,705,600	1,765,100
Stock option related information [Abstract]
Cash paid out on options vested	$ 3,107	$ 2,516	$ 3,107	$ 2,516
Compensation costs recognized	972	$ 1,697	1,607	$ 1,395
Total liability for the Plan	$ 3,400		$ 3,400		$ 4,900