Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - Postretirement Benefits Other Than Pension - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Defined Benefit Plan Disclosure
Service cost	$ 1,195	$ 936	$ 1,972
Interest cost	943	810	969
Expected return on plan assets	0	0	0
Amortization of net loss (gain)	(500)	(880)	7
Amortization of prior service credit	(1,757)	(1,757)	(1,757)
Net periodic benefit (credit) cost	$ (119)	$ (891)	$ 1,191