Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Components of Postretirement Benefit Expense (Income) and Pension (Benefit) Cost (Detail)

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Employee Benefit Plans - Components of Postretirement Benefit Expense (Income) and Pension (Benefit) Cost (Detail) - Other Postretirement Benefit Plans [Member] - USD ($)
$ in Thousands
12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2014
Defined Benefit Plan Disclosure [Line Items]      
Interest cost on projected benefit obligation $ 29 $ 31 $ 33
Unrecognized prior service cost   (106) (166)
Actuarial loss 40 35 46
Net pension (benefit) cost $ 69 $ (40) $ (87)