Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 5	$ 8	$ 11	$ 15
Amortization of net (gain) loss		7		15
Net periodic cost	5	15	11	30
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	28	28	57	56
Amortization of net (gain) loss	3		5
Net periodic cost	$ 31	$ 28	$ 62	$ 56