Employee Benefit Plans

9 Months Ended

Mar. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Employee Benefit Plans

9.     Employee Benefit Plans

The Company maintains a noncontributory defined benefit pension plan for all domestic nonunion employees employed on or prior to December 31, 2013, who meet certain requirements of age, length of service and hours worked per year. Plan benefits are based upon years of service and average compensation, as defined within the plan.

The following table details the net periodic pension expense:

​	Three Months						Nine Months
For the Periods Ended March 31	2015			2014			2015			2014
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