Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - Postretirement Benefits Other Than Pension - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure
Service cost	$ 1,388	$ 1,195	$ 1,388	$ 1,195	$ 936
Interest cost	$ 1,194	$ 943	1,194	943	810
Amortization of net loss (gain)			(196)	(500)	(880)
Amortization of prior service credit			(1,757)	(1,757)	(1,757)
Net periodic benefit (credit) cost			$ 629	$ (119)	$ (891)