Schedule of Net Periodic Pension Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Service cost	$ 938	$ 952
Interest cost	137	107
Expected return on plan assets	(246)	(215)
Net amortization	67	105
Net periodic pension costs	$ 896	$ 949