Employee Benefit Plans - Net periodic pension expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost - benefits earned during the period	$ 739	$ 535	$ 2,217	$ 1,843
Interest cost on benefit obligation	654	532	1,963	1,750
Expected return on plan assets	(707)	(476)	(2,121)	(1,751)
Amortization of net actuarial loss and prior service costs	351	249	1,053	678
Net periodic pension expense	$ 1,037	$ 840	$ 3,112	$ 2,520