Stock-Based Compensation, Phantom Stock Option Plan and Long-term Incentive Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Stock option activity, shares [Roll Forward]
Options granted (in shares)	0	0
2011 Phantom Stock Option and Long-term Incentive Plan [Member]
Share-based Compensation [Abstract]
Number of shares authorized under the plan (in shares)	5,800,000	3,600,000
Number of options granted to date (in shares)	3,567,182	2,972,982
Stock option activity, shares [Roll Forward]
Outstanding at beginning of year (in shares)	1,522,720	1,352,554
Options granted (in shares)	594,200	578,200
Options forfeited (in shares)	(27,000)	0
Options paid in cash upon vesting (in shares)	(455,760)	(408,034)
Outstanding at period end (in shares)	1,634,160	1,522,720
Stock option related information [Abstract]
Cash paid out on options vested	$ 1,187	$ 845
Compensation expense recognized	2,140	1,448
Total liability for long-term incentive plan	$ 3,000	$ 2,000
2011 Phantom Stock Option and Long-term Incentive Plan [Member] | Minimum [Member]
Share-based Compensation [Abstract]
Strike price of phantom stock options as percent of book value	100.00%