Employee Benefit Plans - Net periodic pension expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost - benefits earned during the period	$ 751	$ 656	$ 1,470	$ 1,477
Interest cost on benefit obligation	757	574	1,446	1,309
Expected return on plan assets	(846)	(648)	(1,588)	(1,414)
Amortization of net actuarial (gain) loss and prior service costs	508	417	892	702
Net periodic pension expense	$ 1,170	$ 999	$ 2,220	$ 2,074