Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 4	$ 5	$ 9	$ 11
Net periodic cost	4	5	9	11
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	13	28	26	57
Amortization of net (gain) loss	9	3	18	5
Net periodic cost	$ 22	$ 31	$ 44	$ 62