Pension and Postretirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Components of Net Periodic Benefit Costs [Abstract]
Service cost	$ 2,977	$ 3,043	$ 5,954	$ 6,086
Interest cost	1,469	1,396	2,938	2,792
Expected return on plan assets	(2,746)	(2,759)	(5,492)	(5,518)
Prior service cost amortization	49	56	98	112
Actuarial loss (gain) amortization	157	169	314	338
Net periodic benefit credit	1,906	1,905	3,812	3,810
Postretirement Benefit Plans [Member]
Components of Net Periodic Benefit Costs [Abstract]
Service cost	25	29	50	58
Interest cost	96	102	192	204
Prior service cost amortization	(107)	(108)	(214)	(216)
Actuarial loss (gain) amortization	(169)	(108)	(338)	(216)
Net periodic benefit credit	$ (155)	$ (85)	$ (310)	$ (170)