Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 6	$ 7	$ 17	$ 22
Amortization of net (gain) loss		8		23
Net periodic cost	6	15	17	45
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	27	29	84	85
Amortization of net (gain) loss	2		7
Net periodic cost	$ 29	$ 29	$ 91	$ 85