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, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018
Stock option related information [Abstract]
Total liability for the Plan	$ 3,300		$ 3,300		$ 3,000
Phantom Stock Option [Member]
Stock option activity, shares [Roll Forward]
Outstanding at beginning of period (in shares)	1,742,100	1,634,160	1,634,160	1,522,720
Options granted (in shares)	0	0	592,700	594,200
Options forfeited (in shares)	0	0	0	(27,000)
Options paid in cash (in shares)	(18,000)	0	(502,760)	(455,760)
Outstanding, end of period (in shares)	1,724,100	1,634,160	1,724,100	1,634,160
Stock option related information [Abstract]
Cash paid out on options vested	$ 41	$ 0	$ 1,745	$ 1,187
Compensation costs recognized	$ 810	$ 640	$ 2,021	$ 1,460